<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CommitmentsAndContingencies" xlink:href="ktos-20170625.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CommitmentsAndContingenciesDetails" xlink:href="ktos-20170625.xsd#CommitmentsAndContingenciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheets" xlink:href="ktos-20170625.xsd#CondensedConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:href="ktos-20170625.xsd#CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:href="ktos-20170625.xsd#CondensedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss" xlink:href="ktos-20170625.xsd#CondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingBalanceSheetDetails" xlink:href="ktos-20170625.xsd#CondensedConsolidatingBalanceSheetDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatements" xlink:href="ktos-20170625.xsd#CondensedConsolidatingFinancialStatements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsTables" xlink:href="ktos-20170625.xsd#CondensedConsolidatingFinancialStatementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingStatementOfCashFlowsDetails" xlink:href="ktos-20170625.xsd#CondensedConsolidatingStatementOfCashFlowsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingStatementOfOperationsAndComprehensiveIncomeLossDetails" xlink:href="ktos-20170625.xsd#CondensedConsolidatingStatementOfOperationsAndComprehensiveIncomeLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/Debt" xlink:href="ktos-20170625.xsd#Debt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/Debt1100MillionCreditAgreementDetails" xlink:href="ktos-20170625.xsd#Debt1100MillionCreditAgreementDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtDebtAcquiredInAcquisitionDetails" xlink:href="ktos-20170625.xsd#DebtDebtAcquiredInAcquisitionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtFairValueOfLongTermDebtDetails" xlink:href="ktos-20170625.xsd#DebtFairValueOfLongTermDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtIssuanceOf7SeniorSecuredNotesDue2019Details" xlink:href="ktos-20170625.xsd#DebtIssuanceOf7SeniorSecuredNotesDue2019Details" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtTables" xlink:href="ktos-20170625.xsd#DebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DocumentAndEntityInformation" xlink:href="ktos-20170625.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssets" xlink:href="ktos-20170625.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsGoodwillDetails" xlink:href="ktos-20170625.xsd#GoodwillAndIntangibleAssetsGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsPurchasedIntangibleAssetsDetails" xlink:href="ktos-20170625.xsd#GoodwillAndIntangibleAssetsPurchasedIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="ktos-20170625.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxes" xlink:href="ktos-20170625.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxesAdditionalInformationDetails" xlink:href="ktos-20170625.xsd#IncomeTaxesAdditionalInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxesIncomeTaxProvisionReconciliationDetails" xlink:href="ktos-20170625.xsd#IncomeTaxesIncomeTaxProvisionReconciliationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxesTables" xlink:href="ktos-20170625.xsd#IncomeTaxesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/InventoriedCosts" xlink:href="ktos-20170625.xsd#InventoriedCosts" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/InventoriedCostsDetails" xlink:href="ktos-20170625.xsd#InventoriedCostsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/InventoriedCostsTables" xlink:href="ktos-20170625.xsd#InventoriedCostsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/NetLossPerCommonShare" xlink:href="ktos-20170625.xsd#NetLossPerCommonShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/NetLossPerCommonShareDetails" xlink:href="ktos-20170625.xsd#NetLossPerCommonShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformation" xlink:href="ktos-20170625.xsd#SegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformationAdditionalInformationDetails" xlink:href="ktos-20170625.xsd#SegmentInformationAdditionalInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformationScheduleOfSegmentRevenuesDepreciationAndAmortizationAndOperatingLossDetails" xlink:href="ktos-20170625.xsd#SegmentInformationScheduleOfSegmentRevenuesDepreciationAndAmortizationAndOperatingLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformationTables" xlink:href="ktos-20170625.xsd#SegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SignificantCustomers" xlink:href="ktos-20170625.xsd#SignificantCustomers" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SignificantCustomersDetails" xlink:href="ktos-20170625.xsd#SignificantCustomersDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquity" xlink:href="ktos-20170625.xsd#StockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquityAccumulatedOtherComprehensiveLossDetails" xlink:href="ktos-20170625.xsd#StockholdersEquityAccumulatedOtherComprehensiveLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquityRollforwardOfCommonStockOutstandingDetails" xlink:href="ktos-20170625.xsd#StockholdersEquityRollforwardOfCommonStockOutstandingDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquitySummaryOfChangesInStockholdersEquityDetails" xlink:href="ktos-20170625.xsd#StockholdersEquitySummaryOfChangesInStockholdersEquityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquityTables" xlink:href="ktos-20170625.xsd#StockholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="ktos-20170625.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:href="ktos-20170625.xsd#SummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="ktos-20170625.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CommitmentsAndContingenciesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_98383DC9051FDBDE66D46134AEFA0238" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_67A622DB24C984A2E01A6134AEFAE378" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_98383DC9051FDBDE66D46134AEFA0238" xlink:to="loc_us-gaap_LossContingenciesTable_67A622DB24C984A2E01A6134AEFAE378" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_E0C5E5D44D6CBD9604586134AEFA0143" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_67A622DB24C984A2E01A6134AEFAE378" xlink:to="loc_us-gaap_LitigationStatusAxis_E0C5E5D44D6CBD9604586134AEFA0143" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_CD85A32747608A5B26FC6134AEFA4C75_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_E0C5E5D44D6CBD9604586134AEFA0143" xlink:to="loc_us-gaap_LitigationStatusDomain_CD85A32747608A5B26FC6134AEFA4C75_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_CD85A32747608A5B26FC6134AEFA4C75" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_E0C5E5D44D6CBD9604586134AEFA0143" xlink:to="loc_us-gaap_LitigationStatusDomain_CD85A32747608A5B26FC6134AEFA4C75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SettledLitigationMember" xlink:label="loc_us-gaap_SettledLitigationMember_D22F0084EC99BD178B216134AEFA96A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_CD85A32747608A5B26FC6134AEFA4C75" xlink:to="loc_us-gaap_SettledLitigationMember_D22F0084EC99BD178B216134AEFA96A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_82A76CB7F178D5BC8B186134AEFA7496" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_67A622DB24C984A2E01A6134AEFAE378" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_82A76CB7F178D5BC8B186134AEFA7496" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_0671F973F132775E25596134AEFAAB80_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_82A76CB7F178D5BC8B186134AEFA7496" xlink:to="loc_us-gaap_SegmentDomain_0671F973F132775E25596134AEFAAB80_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_0671F973F132775E25596134AEFAAB80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_82A76CB7F178D5BC8B186134AEFA7496" xlink:to="loc_us-gaap_SegmentDomain_0671F973F132775E25596134AEFAAB80" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_10D65886540F33B9F99F6134AEFA07EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0671F973F132775E25596134AEFAAB80" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_10D65886540F33B9F99F6134AEFA07EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_328EACB5437E3AB9B3806134AEFA6DE0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_98383DC9051FDBDE66D46134AEFA0238" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_328EACB5437E3AB9B3806134AEFA6DE0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationSettlementExpense" xlink:label="loc_us-gaap_LitigationSettlementExpense_090C02527ACD19E4B4076134AEFA784B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_98383DC9051FDBDE66D46134AEFA0238" xlink:to="loc_us-gaap_LitigationSettlementExpense_090C02527ACD19E4B4076134AEFA784B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingBalanceSheetDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CondensedFinancialStatementsCaptionsLineItems" xlink:label="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_9199F4C3308717F128526134AEEEB297" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfCondensedFinancialStatementsTable" xlink:label="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_82E4D16A28CAE0B17E716134AEEC927D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_9199F4C3308717F128526134AEEEB297" xlink:to="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_82E4D16A28CAE0B17E716134AEEC927D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_481154D6111C32972B156134AEECF868" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_82E4D16A28CAE0B17E716134AEEC927D" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_481154D6111C32972B156134AEECF868" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4FCCA6C55FD8ADCF7FDF6134AEECF916_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_481154D6111C32972B156134AEECF868" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4FCCA6C55FD8ADCF7FDF6134AEECF916_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4FCCA6C55FD8ADCF7FDF6134AEECF916" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_481154D6111C32972B156134AEECF868" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4FCCA6C55FD8ADCF7FDF6134AEECF916" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_EC576BB1329EE02538986134AEECE2CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_4FCCA6C55FD8ADCF7FDF6134AEECF916" xlink:to="loc_us-gaap_SeniorNotesMember_EC576BB1329EE02538986134AEECE2CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_159F2D0BC0EC084693576134AEEC22DD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_82E4D16A28CAE0B17E716134AEEC927D" xlink:to="loc_us-gaap_DebtInstrumentAxis_159F2D0BC0EC084693576134AEEC22DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8FAC9B34632909AB07976134AEEC2025_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_159F2D0BC0EC084693576134AEEC22DD" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8FAC9B34632909AB07976134AEEC2025_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8FAC9B34632909AB07976134AEEC2025" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_159F2D0BC0EC084693576134AEEC22DD" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8FAC9B34632909AB07976134AEEC2025" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_SevenPercentSeniorNotesDue2019Member" xlink:label="loc_ktos_SevenPercentSeniorNotesDue2019Member_B4F640F7C62D3059513C6134AEED9CE1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8FAC9B34632909AB07976134AEEC2025" xlink:to="loc_ktos_SevenPercentSeniorNotesDue2019Member_B4F640F7C62D3059513C6134AEED9CE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesAxis" xlink:label="loc_us-gaap_ConsolidatedEntitiesAxis_DF31E695525BD148BFF46134AEEDE9EA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_82E4D16A28CAE0B17E716134AEEC927D" xlink:to="loc_us-gaap_ConsolidatedEntitiesAxis_DF31E695525BD148BFF46134AEEDE9EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesDomain" xlink:label="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidatedEntitiesAxis_DF31E695525BD148BFF46134AEEDE9EA" xlink:to="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesDomain" xlink:label="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidatedEntitiesAxis_DF31E695525BD148BFF46134AEEDE9EA" xlink:to="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsidiariesMember" xlink:label="loc_us-gaap_SubsidiariesMember_6153266946854F65E2066134AEED14C6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE" xlink:to="loc_us-gaap_SubsidiariesMember_6153266946854F65E2066134AEED14C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ParentCompanyMember" xlink:label="loc_us-gaap_ParentCompanyMember_D32598641AE52F68C2D06134AEED39BA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE" xlink:to="loc_us-gaap_ParentCompanyMember_D32598641AE52F68C2D06134AEED39BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GuarantorSubsidiariesMember" xlink:label="loc_us-gaap_GuarantorSubsidiariesMember_4536DA5956DAF262E8D96134AEEDEE89" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE" xlink:to="loc_us-gaap_GuarantorSubsidiariesMember_4536DA5956DAF262E8D96134AEEDEE89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NonGuarantorSubsidiariesMember" xlink:label="loc_us-gaap_NonGuarantorSubsidiariesMember_14D293C4893D6B6387356134AEED74A2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_6C492759D2331C145D496134AEED91FE" xlink:to="loc_us-gaap_NonGuarantorSubsidiariesMember_14D293C4893D6B6387356134AEED74A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_7D1E2E7A6BE998C8A4746134AEEDCAF2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_82E4D16A28CAE0B17E716134AEEC927D" xlink:to="loc_us-gaap_ConsolidationItemsAxis_7D1E2E7A6BE998C8A4746134AEEDCAF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_380467F5B92A41360C496134AEEDC1B7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_7D1E2E7A6BE998C8A4746134AEEDCAF2" xlink:to="loc_us-gaap_ConsolidationItemsDomain_380467F5B92A41360C496134AEEDC1B7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_380467F5B92A41360C496134AEEDC1B7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_7D1E2E7A6BE998C8A4746134AEEDCAF2" xlink:to="loc_us-gaap_ConsolidationItemsDomain_380467F5B92A41360C496134AEEDC1B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationEliminationsMember" xlink:label="loc_us-gaap_ConsolidationEliminationsMember_B4C304D0F187A37FC7C86134AEEE542D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_380467F5B92A41360C496134AEEDC1B7" xlink:to="loc_us-gaap_ConsolidationEliminationsMember_B4C304D0F187A37FC7C86134AEEE542D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_9D53916D7C3DF37120D06134AEEE0508" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_9199F4C3308717F128526134AEEEB297" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_9D53916D7C3DF37120D06134AEEE0508" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_6DF109372C990516AA9E6134AEEE48A7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_9199F4C3308717F128526134AEEEB297" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_6DF109372C990516AA9E6134AEEE48A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_9199F4C3308717F128526134AEEEB297" xlink:to="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:to="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_CA079CB6637BC0D048696134AEEEBCC4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_CA079CB6637BC0D048696134AEEEBCC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_CBCD68560539DD4098F36134AEEE60D8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_CBCD68560539DD4098F36134AEEE60D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DueFromAffiliateCurrent" xlink:label="loc_us-gaap_DueFromAffiliateCurrent_FD7B66117F48D4DC52816134AEEF37CA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:to="loc_us-gaap_DueFromAffiliateCurrent_FD7B66117F48D4DC52816134AEEF37CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings" xlink:label="loc_us-gaap_InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings_1161300B059FC95225DF6134AEEFD65E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:to="loc_us-gaap_InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings_1161300B059FC95225DF6134AEEFD65E" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_RestrictedCashAndCashEquivalentsAtCarryingValuePrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_ktos_RestrictedCashAndCashEquivalentsAtCarryingValuePrepaidExpenseAndOtherAssetsCurrent_EC19AA4519C34408C6DB6134AEEFEC75" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:to="loc_ktos_RestrictedCashAndCashEquivalentsAtCarryingValuePrepaidExpenseAndOtherAssetsCurrent_EC19AA4519C34408C6DB6134AEEFEC75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_451D8C41B13D5F791ADB6134AEEF756A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_77B787C7F403B359B8DF6134AEEE7B1B" xlink:to="loc_us-gaap_AssetsCurrent_451D8C41B13D5F791ADB6134AEEF756A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_F48138F18296D0BDD74A6134AEEFC5E3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_F48138F18296D0BDD74A6134AEEFC5E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_B51350BD382E9D8ADC966134AEEFBB7C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:to="loc_us-gaap_Goodwill_B51350BD382E9D8ADC966134AEEFBB7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_906F032D666A6B8DC73A6134AEEF4925" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_906F032D666A6B8DC73A6134AEEF4925" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_F2ADA85B279580AF62306134AEEFADB9" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_F2ADA85B279580AF62306134AEEFADB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_73609FB93CCE42A0745F6134AEEF6E5B" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_73609FB93CCE42A0745F6134AEEF6E5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_8F4C4A561AEB3FAC57536134AEEF239E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_891B5142CFAB82EC8D456134AEEEF961" xlink:to="loc_us-gaap_Assets_8F4C4A561AEB3FAC57536134AEEF239E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_9199F4C3308717F128526134AEEEB297" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_302B33204D54ECF69C816134AEEFA0C7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_us-gaap_AccountsPayableCurrent_302B33204D54ECF69C816134AEEFA0C7" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_AccruedExpensesCurrent" xlink:label="loc_ktos_AccruedExpensesCurrent_4092549FB4B39DE252286134AEEFC2E0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_ktos_AccruedExpensesCurrent_4092549FB4B39DE252286134AEEFC2E0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_F281A252099D9DBA7C316134AEEF6CD0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_F281A252099D9DBA7C316134AEEF6CD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BillingsInExcessOfCost" xlink:label="loc_us-gaap_BillingsInExcessOfCost_30DBCC48F0C391C743E66134AEF022EE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_us-gaap_BillingsInExcessOfCost_30DBCC48F0C391C743E66134AEF022EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DueToAffiliateCurrent" xlink:label="loc_us-gaap_DueToAffiliateCurrent_CEFFE76D1C9A7FD4A63C6134AEF026EA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_us-gaap_DueToAffiliateCurrent_CEFFE76D1C9A7FD4A63C6134AEF026EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_101C957ECE40ED5DC16E6134AEF04281" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_101C957ECE40ED5DC16E6134AEF04281" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_6C4D1E1E21C2D4BCBC3D6134AEF00B89" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_6C4D1E1E21C2D4BCBC3D6134AEF00B89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_676C2EAC5740CE97D80A6134AEF09FA6" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_5253A39971BB739F81996134AEEF23E8" xlink:to="loc_us-gaap_LiabilitiesCurrent_676C2EAC5740CE97D80A6134AEF09FA6" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_LongTermDebtAndUnamortizedPremiumNoncurrent" xlink:label="loc_ktos_LongTermDebtAndUnamortizedPremiumNoncurrent_37C16D0B2D63AE359D366134AEF01888" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:to="loc_ktos_LongTermDebtAndUnamortizedPremiumNoncurrent_37C16D0B2D63AE359D366134AEF01888" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_E02DF83B5734B4123AD96134AEF0E24B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_E02DF83B5734B4123AD96134AEF0E24B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_3EFBD59CB90CE7670EE06134AEF0BA53" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_3EFBD59CB90CE7670EE06134AEF0BA53" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_14A55ED3BF4FAE73288F6134AEF07A35" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:to="loc_us-gaap_Liabilities_14A55ED3BF4FAE73288F6134AEF07A35" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_C351ED889B3571FF73096134AEF083F4" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_C351ED889B3571FF73096134AEF083F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_E9380B1BA0B2803BE14E6134AEF0C149" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_04820632FD90E6C2F2A06134AEEF27AC" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_E9380B1BA0B2803BE14E6134AEF0C149" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingStatementOfCashFlowsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CondensedFinancialStatementsCaptionsLineItems" xlink:label="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfCondensedFinancialStatementsTable" xlink:label="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_20EA3EE45A3435BE165D84C46EA9E09A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_20EA3EE45A3435BE165D84C46EA9E09A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_A45DA8F7C9201A4CEE2E84C46EA9B8C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_20EA3EE45A3435BE165D84C46EA9E09A" xlink:to="loc_dei_LegalEntityAxis_A45DA8F7C9201A4CEE2E84C46EA9B8C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_8E89BB941C767C23B92A84C46EA96D1B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_A45DA8F7C9201A4CEE2E84C46EA9B8C0" xlink:to="loc_dei_EntityDomain_8E89BB941C767C23B92A84C46EA96D1B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_8E89BB941C767C23B92A84C46EA96D1B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_A45DA8F7C9201A4CEE2E84C46EA9B8C0" xlink:to="loc_dei_EntityDomain_8E89BB941C767C23B92A84C46EA96D1B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesAxis" xlink:label="loc_us-gaap_ConsolidatedEntitiesAxis_A25F08F2C8FA35C069BF84C46EA91357" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_20EA3EE45A3435BE165D84C46EA9E09A" xlink:to="loc_us-gaap_ConsolidatedEntitiesAxis_A25F08F2C8FA35C069BF84C46EA91357" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesDomain" xlink:label="loc_us-gaap_ConsolidatedEntitiesDomain_B0A6D9BDE333F3C05FD784C46EA9B3C8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidatedEntitiesAxis_A25F08F2C8FA35C069BF84C46EA91357" xlink:to="loc_us-gaap_ConsolidatedEntitiesDomain_B0A6D9BDE333F3C05FD784C46EA9B3C8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesDomain" xlink:label="loc_us-gaap_ConsolidatedEntitiesDomain_B0A6D9BDE333F3C05FD784C46EA9B3C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidatedEntitiesAxis_A25F08F2C8FA35C069BF84C46EA91357" xlink:to="loc_us-gaap_ConsolidatedEntitiesDomain_B0A6D9BDE333F3C05FD784C46EA9B3C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ParentCompanyMember" xlink:label="loc_us-gaap_ParentCompanyMember_861FF498CD47AF9BC82384C46EA998D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_B0A6D9BDE333F3C05FD784C46EA9B3C8" xlink:to="loc_us-gaap_ParentCompanyMember_861FF498CD47AF9BC82384C46EA998D6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GuarantorSubsidiariesMember" xlink:label="loc_us-gaap_GuarantorSubsidiariesMember_55435BC0B4BF0018248B84C46EA9484F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_B0A6D9BDE333F3C05FD784C46EA9B3C8" xlink:to="loc_us-gaap_GuarantorSubsidiariesMember_55435BC0B4BF0018248B84C46EA9484F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NonGuarantorSubsidiariesMember" xlink:label="loc_us-gaap_NonGuarantorSubsidiariesMember_3FF1C42F322A33BA06D884C46EA98AE7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_B0A6D9BDE333F3C05FD784C46EA9B3C8" xlink:to="loc_us-gaap_NonGuarantorSubsidiariesMember_3FF1C42F322A33BA06D884C46EA98AE7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_C1B151ABF9363A52286E84C46EA96FB6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_20EA3EE45A3435BE165D84C46EA9E09A" xlink:to="loc_us-gaap_ConsolidationItemsAxis_C1B151ABF9363A52286E84C46EA96FB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_A1BD7AF5CFB06D0B79FF84C46EA910BB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_C1B151ABF9363A52286E84C46EA96FB6" xlink:to="loc_us-gaap_ConsolidationItemsDomain_A1BD7AF5CFB06D0B79FF84C46EA910BB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_A1BD7AF5CFB06D0B79FF84C46EA910BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_C1B151ABF9363A52286E84C46EA96FB6" xlink:to="loc_us-gaap_ConsolidationItemsDomain_A1BD7AF5CFB06D0B79FF84C46EA910BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationEliminationsMember" xlink:label="loc_us-gaap_ConsolidationEliminationsMember_5569A37DB7333AD5BD9284C46EA9F696" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_A1BD7AF5CFB06D0B79FF84C46EA910BB" xlink:to="loc_us-gaap_ConsolidationEliminationsMember_5569A37DB7333AD5BD9284C46EA9F696" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations_7DB6D18D2E2CBF7C8CB784C46EA9F2BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations_7DB6D18D2E2CBF7C8CB784C46EA9F2BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_0DED203CB8E256A013BF84C46EAADFC3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_0DED203CB8E256A013BF84C46EAADFC3" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_PaymentsForProceedsFromInvestmentInAffiliatedCompanies" xlink:label="loc_ktos_PaymentsForProceedsFromInvestmentInAffiliatedCompanies_2923A7858566289C281284C46EAAE83C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_0DED203CB8E256A013BF84C46EAADFC3" xlink:to="loc_ktos_PaymentsForProceedsFromInvestmentInAffiliatedCompanies_2923A7858566289C281284C46EAAE83C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncreaseDecreaseInRestrictedCash" xlink:label="loc_us-gaap_IncreaseDecreaseInRestrictedCash_67B5E519D4878EE6047684C46EAAFF3C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_0DED203CB8E256A013BF84C46EAADFC3" xlink:to="loc_us-gaap_IncreaseDecreaseInRestrictedCash_67B5E519D4878EE6047684C46EAAFF3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsForProceedsFromProductiveAssets" xlink:label="loc_us-gaap_PaymentsForProceedsFromProductiveAssets_3CCB07E3F74CC2C226ED84C46EAABA18" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_0DED203CB8E256A013BF84C46EAADFC3" xlink:to="loc_us-gaap_PaymentsForProceedsFromProductiveAssets_3CCB07E3F74CC2C226ED84C46EAABA18" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_21549DBEB2E6F0E6A8E184C46EAA550F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_0DED203CB8E256A013BF84C46EAADFC3" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_21549DBEB2E6F0E6A8E184C46EAA550F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_5781F2F6C6C07870FFCA84C46EAAEB66" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_5781F2F6C6C07870FFCA84C46EAAEB66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_DFD023CD2D9CCE02ABC984C46EAAA237" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_DFD023CD2D9CCE02ABC984C46EAAA237" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_601F413F5E4B0BC4C6F184C46EAA68C2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_601F413F5E4B0BC4C6F184C46EAA68C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromRepurchaseOfEquity" xlink:label="loc_us-gaap_ProceedsFromRepurchaseOfEquity_4E0BA3ECF0985DC7223184C46EAA6794" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:to="loc_us-gaap_ProceedsFromRepurchaseOfEquity_4E0BA3ECF0985DC7223184C46EAA6794" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromContributionsFromAffiliates" xlink:label="loc_us-gaap_ProceedsFromContributionsFromAffiliates_E8350865E4C00010B66984C46EAA58FA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:to="loc_us-gaap_ProceedsFromContributionsFromAffiliates_E8350865E4C00010B66984C46EAA58FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_16194CC46A438A66B50584C46EAB6BFD" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_155480FC21F98C9FE95284C46EAAC938" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_16194CC46A438A66B50584C46EAB6BFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInContinuingOperations_5EA5B3F9D9F07B4D0BD584C46EABB3B2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_NetCashProvidedByUsedInContinuingOperations_5EA5B3F9D9F07B4D0BD584C46EABB3B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" xlink:label="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations_6954C85AF23DF1BAF94584C46EABA46A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations_6954C85AF23DF1BAF94584C46EABA46A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" xlink:label="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_342B7DC8DE3D0C3D35EA84C46EAB19E6" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_342B7DC8DE3D0C3D35EA84C46EAB19E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalentsContinuingOperations" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalentsContinuingOperations_669C5A60073C26C44DE484C46EABFD76" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalentsContinuingOperations_669C5A60073C26C44DE484C46EABFD76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_53F5E12D15C8F90BB4C784C46EAB03BF" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_764C693B0B530AE559BA84C46EA9F1AB" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_53F5E12D15C8F90BB4C784C46EAB03BF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingStatementOfOperationsAndComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CondensedFinancialStatementsCaptionsLineItems" xlink:label="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfCondensedFinancialStatementsTable" xlink:label="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F3C57C66D38C554185F26134AEDB0BDA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F3C57C66D38C554185F26134AEDB0BDA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesAxis" xlink:label="loc_us-gaap_ConsolidatedEntitiesAxis_8765F4BA8888AD45E8E86134AEDC907A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F3C57C66D38C554185F26134AEDB0BDA" xlink:to="loc_us-gaap_ConsolidatedEntitiesAxis_8765F4BA8888AD45E8E86134AEDC907A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesDomain" xlink:label="loc_us-gaap_ConsolidatedEntitiesDomain_1A9531EE1E215EB6C5346134AEDCBB3A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidatedEntitiesAxis_8765F4BA8888AD45E8E86134AEDC907A" xlink:to="loc_us-gaap_ConsolidatedEntitiesDomain_1A9531EE1E215EB6C5346134AEDCBB3A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesDomain" xlink:label="loc_us-gaap_ConsolidatedEntitiesDomain_1A9531EE1E215EB6C5346134AEDCBB3A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidatedEntitiesAxis_8765F4BA8888AD45E8E86134AEDC907A" xlink:to="loc_us-gaap_ConsolidatedEntitiesDomain_1A9531EE1E215EB6C5346134AEDCBB3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ParentCompanyMember" xlink:label="loc_us-gaap_ParentCompanyMember_79354DC1E3F4006971EF6134AEDCA2B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_1A9531EE1E215EB6C5346134AEDCBB3A" xlink:to="loc_us-gaap_ParentCompanyMember_79354DC1E3F4006971EF6134AEDCA2B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GuarantorSubsidiariesMember" xlink:label="loc_us-gaap_GuarantorSubsidiariesMember_899D72FD8AF855E180456134AEDCDEA0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_1A9531EE1E215EB6C5346134AEDCBB3A" xlink:to="loc_us-gaap_GuarantorSubsidiariesMember_899D72FD8AF855E180456134AEDCDEA0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NonGuarantorSubsidiariesMember" xlink:label="loc_us-gaap_NonGuarantorSubsidiariesMember_5619FEF42420EA9416936134AEDCFC81" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidatedEntitiesDomain_1A9531EE1E215EB6C5346134AEDCBB3A" xlink:to="loc_us-gaap_NonGuarantorSubsidiariesMember_5619FEF42420EA9416936134AEDCFC81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_0CFC56739A4504C6C2266134AEDCA705" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F3C57C66D38C554185F26134AEDB0BDA" xlink:to="loc_us-gaap_ConsolidationItemsAxis_0CFC56739A4504C6C2266134AEDCA705" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_D75BC1323606CA2504106134AEDC9A3D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_0CFC56739A4504C6C2266134AEDCA705" xlink:to="loc_us-gaap_ConsolidationItemsDomain_D75BC1323606CA2504106134AEDC9A3D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_D75BC1323606CA2504106134AEDC9A3D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_0CFC56739A4504C6C2266134AEDCA705" xlink:to="loc_us-gaap_ConsolidationItemsDomain_D75BC1323606CA2504106134AEDC9A3D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationEliminationsMember" xlink:label="loc_us-gaap_ConsolidationEliminationsMember_12CF19C2B0B98EE1CDFA6134AEDCAFF6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_D75BC1323606CA2504106134AEDC9A3D" xlink:to="loc_us-gaap_ConsolidationEliminationsMember_12CF19C2B0B98EE1CDFA6134AEDCAFF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueServicesNet" xlink:label="loc_us-gaap_SalesRevenueServicesNet_8A96AD6EBF1274E6D3E96134AEDDAC1B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_SalesRevenueServicesNet_8A96AD6EBF1274E6D3E96134AEDDAC1B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:label="loc_us-gaap_SalesRevenueGoodsNet_327BDAD8923CC7C43C586134AEDDA8F3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_SalesRevenueGoodsNet_327BDAD8923CC7C43C586134AEDDA8F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_331C6573B9A0765946216134AEDD94C9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_SalesRevenueNet_331C6573B9A0765946216134AEDD94C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostOfServices" xlink:label="loc_us-gaap_CostOfServices_5C001D332656E18F916E6134AEDDE24B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_CostOfServices_5C001D332656E18F916E6134AEDDE24B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostOfGoodsSold" xlink:label="loc_us-gaap_CostOfGoodsSold_DDFFC03179A0B4C0BADC6134AEDD566F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_CostOfGoodsSold_DDFFC03179A0B4C0BADC6134AEDD566F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_2116DE6613DA6D02C5146134AEDD6414" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_CostOfRevenue_2116DE6613DA6D02C5146134AEDD6414" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_224CAB64B34C69F198676134AEDD8719" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_GrossProfit_224CAB64B34C69F198676134AEDD8719" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_SellingGeneralAndAdministrativeExpenseBusinessAcquisitionRelatedCostsAndOtherImpairmentCharges" xlink:label="loc_ktos_SellingGeneralAndAdministrativeExpenseBusinessAcquisitionRelatedCostsAndOtherImpairmentCharges_8EE4DB7BA5BA827D007C6134AEDD95D2" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_ktos_SellingGeneralAndAdministrativeExpenseBusinessAcquisitionRelatedCostsAndOtherImpairmentCharges_8EE4DB7BA5BA827D007C6134AEDD95D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_202E0E99ACEE8D0491366134AEDDB3AA" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_202E0E99ACEE8D0491366134AEDDB3AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_F7E86AA168805D5E6C256134AEDD8A9A" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_OperatingIncomeLoss_F7E86AA168805D5E6C256134AEDD8A9A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseAbstract" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_7A878263B26CB7B76DD96134AEDD0D5C" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_7A878263B26CB7B76DD96134AEDD0D5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_84C3275AF59BD6B8356E6134AEDD69E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_7A878263B26CB7B76DD96134AEDD0D5C" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_84C3275AF59BD6B8356E6134AEDD69E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_37B177EFF4E77CBDAAC66134AEDE11A6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_7A878263B26CB7B76DD96134AEDD0D5C" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_37B177EFF4E77CBDAAC66134AEDE11A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_70F86650573F76FE18EF6134AEDEB6EF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_7A878263B26CB7B76DD96134AEDD0D5C" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_70F86650573F76FE18EF6134AEDEB6EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_881C9A3B7721E04767146134AEDE8F2D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_7A878263B26CB7B76DD96134AEDD0D5C" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_881C9A3B7721E04767146134AEDE8F2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_655F0D17B9E4616C047C6134AEDE380B" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_655F0D17B9E4616C047C6134AEDE380B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_8F5D5CB7ED497849DE6A6134AEDE83CB" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_8F5D5CB7ED497849DE6A6134AEDE83CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_6D4521A864DA774B60A26134AEDE63A7" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_6D4521A864DA774B60A26134AEDE63A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_40B4F9CADF3DF011A6496134AEDE71A1" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_40B4F9CADF3DF011A6496134AEDE71A1" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_EquityInNetIncomeLossOfSubsidiaries" xlink:label="loc_ktos_EquityInNetIncomeLossOfSubsidiaries_13B578E0AABA510A9DF26134AEDF497E" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_ktos_EquityInNetIncomeLossOfSubsidiaries_13B578E0AABA510A9DF26134AEDF497E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_F1BCB57129B9885FD6D56134AEDF1215" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_NetIncomeLoss_F1BCB57129B9885FD6D56134AEDF1215" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_E8DD6ACD823A91E84BA86134AEDF4743" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_AFEAB6BB45A30B1412DF6134AEDDD845" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_E8DD6ACD823A91E84BA86134AEDF4743" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/Debt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/Debt1100MillionCreditAgreementDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_C95B07BD966F89D7EB8F6134AF262CDE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:to="loc_us-gaap_StatementScenarioAxis_C95B07BD966F89D7EB8F6134AF262CDE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_D73E6E2DF8BED4A01E536134AF27BC9D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_C95B07BD966F89D7EB8F6134AF262CDE" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_D73E6E2DF8BED4A01E536134AF27BC9D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_D73E6E2DF8BED4A01E536134AF27BC9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_C95B07BD966F89D7EB8F6134AF262CDE" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_D73E6E2DF8BED4A01E536134AF27BC9D" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_ScenarioOneMember" xlink:label="loc_ktos_ScenarioOneMember_C702E81F00C72573D2946134AF27B392" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_D73E6E2DF8BED4A01E536134AF27BC9D" xlink:to="loc_ktos_ScenarioOneMember_C702E81F00C72573D2946134AF27B392" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_ScenarioTwoMember" xlink:label="loc_ktos_ScenarioTwoMember_7A3B65D1E9E3D3D304246134AF276551" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_D73E6E2DF8BED4A01E536134AF27BC9D" xlink:to="loc_ktos_ScenarioTwoMember_7A3B65D1E9E3D3D304246134AF276551" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_ScenarioFiveMember" xlink:label="loc_ktos_ScenarioFiveMember_A649C54EA899B2213AE36134AF277D62" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_D73E6E2DF8BED4A01E536134AF27BC9D" xlink:to="loc_ktos_ScenarioFiveMember_A649C54EA899B2213AE36134AF277D62" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_ScenarioThreeMember" xlink:label="loc_ktos_ScenarioThreeMember_3EC7CFB49EF748E41E576134AF278D44" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ktos_ScenarioFiveMember_A649C54EA899B2213AE36134AF277D62" xlink:to="loc_ktos_ScenarioThreeMember_3EC7CFB49EF748E41E576134AF278D44" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_ScenarioFourMember" xlink:label="loc_ktos_ScenarioFourMember_64A8C562175D845C2E646134AF27C0DB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ktos_ScenarioFiveMember_A649C54EA899B2213AE36134AF277D62" xlink:to="loc_ktos_ScenarioFourMember_64A8C562175D845C2E646134AF27C0DB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_373FFC6326F966EDEB726134AF274AA3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:to="loc_us-gaap_CreditFacilityAxis_373FFC6326F966EDEB726134AF274AA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_373FFC6326F966EDEB726134AF274AA3" xlink:to="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_373FFC6326F966EDEB726134AF274AA3" xlink:to="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_E0F23CD3D6CE4A3F2F9B6134AF274608" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_E0F23CD3D6CE4A3F2F9B6134AF274608" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember_7670CA1E5EFB316E94C66134AF27BD29" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527" xlink:to="loc_us-gaap_LetterOfCreditMember_7670CA1E5EFB316E94C66134AF27BD29" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_SwingLineLoanMember" xlink:label="loc_ktos_SwingLineLoanMember_0315DBE1B1CEB605FEBD6134AF27082C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527" xlink:to="loc_ktos_SwingLineLoanMember_0315DBE1B1CEB605FEBD6134AF27082C" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_RevolvingLoanSwinglineLoanandLineofCreditMember" xlink:label="loc_ktos_RevolvingLoanSwinglineLoanandLineofCreditMember_A883CF1ABA6D8755058B6134AF27DB8A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0D22A941C3DACBCA283B6134AF270527" xlink:to="loc_ktos_RevolvingLoanSwinglineLoanandLineofCreditMember_A883CF1ABA6D8755058B6134AF27DB8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_A6BE4630E426B698CF936134AF278FD7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:to="loc_us-gaap_VariableRateAxis_A6BE4630E426B698CF936134AF278FD7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_A6BE4630E426B698CF936134AF278FD7" xlink:to="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_A6BE4630E426B698CF936134AF278FD7" xlink:to="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FederalFundsEffectiveSwapRateMember" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember_EC590CC9A961DFBB7EA26134AF27CFC0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A" xlink:to="loc_us-gaap_FederalFundsEffectiveSwapRateMember_EC590CC9A961DFBB7EA26134AF27CFC0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_DDD6F54F323508C8D27B6134AF2836E4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_DDD6F54F323508C8D27B6134AF2836E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BaseRateMember" xlink:label="loc_us-gaap_BaseRateMember_78D84656E17757654E246134AF281FF1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A" xlink:to="loc_us-gaap_BaseRateMember_78D84656E17757654E246134AF281FF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EurodollarMember" xlink:label="loc_us-gaap_EurodollarMember_A2F654BB7831963E460A6134AF2827E6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_3A5ABAE8CE159A3160226134AF27B16A" xlink:to="loc_us-gaap_EurodollarMember_A2F654BB7831963E460A6134AF2827E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_256DAE8FADB8ADF398C16134AF28C496" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:to="loc_us-gaap_RangeAxis_256DAE8FADB8ADF398C16134AF28C496" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_5DB70CC2642986491A5F6134AF28A204_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_256DAE8FADB8ADF398C16134AF28C496" xlink:to="loc_us-gaap_RangeMember_5DB70CC2642986491A5F6134AF28A204_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_5DB70CC2642986491A5F6134AF28A204" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_256DAE8FADB8ADF398C16134AF28C496" xlink:to="loc_us-gaap_RangeMember_5DB70CC2642986491A5F6134AF28A204" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_78332905E0CB529A90906134AF28921D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_5DB70CC2642986491A5F6134AF28A204" xlink:to="loc_us-gaap_MinimumMember_78332905E0CB529A90906134AF28921D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_0E04C807FF155BF4FA4D6134AF28E596" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_5DB70CC2642986491A5F6134AF28A204" xlink:to="loc_us-gaap_MaximumMember_0E04C807FF155BF4FA4D6134AF28E596" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_AFC862EB9932F520C78D6134AF28A1C9" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:to="loc_us-gaap_DebtInstrumentAxis_AFC862EB9932F520C78D6134AF28A1C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5A955001FCB39F310F996134AF28DCEB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_AFC862EB9932F520C78D6134AF28A1C9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5A955001FCB39F310F996134AF28DCEB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5A955001FCB39F310F996134AF28DCEB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_AFC862EB9932F520C78D6134AF28A1C9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5A955001FCB39F310F996134AF28DCEB" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_TwoThousandFourteenCreditAgreementThirdAmendmentMember" xlink:label="loc_ktos_TwoThousandFourteenCreditAgreementThirdAmendmentMember_215AC88BAE6FFBE4CEBE6134AF283EF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5A955001FCB39F310F996134AF28DCEB" xlink:to="loc_ktos_TwoThousandFourteenCreditAgreementThirdAmendmentMember_215AC88BAE6FFBE4CEBE6134AF283EF9" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_TwoThousandFourteenCreditAgreementFourthAmendmentMember" xlink:label="loc_ktos_TwoThousandFourteenCreditAgreementFourthAmendmentMember_F2B3DBCDFA4E4F6C3C5C6134AF283A09" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5A955001FCB39F310F996134AF28DCEB" xlink:to="loc_ktos_TwoThousandFourteenCreditAgreementFourthAmendmentMember_F2B3DBCDFA4E4F6C3C5C6134AF283A09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_14A317767BD159C2F9856134AF28DF04" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_5DDB85CD8534B3C4363B6134AF26DEFC" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_14A317767BD159C2F9856134AF28DF04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_59A62B03866DA6BFE58E6134AF29D074_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_14A317767BD159C2F9856134AF28DF04" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_59A62B03866DA6BFE58E6134AF29D074_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_59A62B03866DA6BFE58E6134AF29D074" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_14A317767BD159C2F9856134AF28DF04" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_59A62B03866DA6BFE58E6134AF29D074" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_HerleyIndustriesIncMember" xlink:label="loc_ktos_HerleyIndustriesIncMember_959275C633C5611755306134AF295650" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_59A62B03866DA6BFE58E6134AF29D074" xlink:to="loc_ktos_HerleyIndustriesIncMember_959275C633C5611755306134AF295650" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_DA05974DAA8689F672296134AF29F729" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_DA05974DAA8689F672296134AF29F729" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentMaturityPeriod" xlink:label="loc_ktos_DebtInstrumentMaturityPeriod_1753E3CEB8B38D16BCAB6134AF29030B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_DebtInstrumentMaturityPeriod_1753E3CEB8B38D16BCAB6134AF29030B" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_LineOfCreditFacilityMaximumPossibleBorrowingsSubjectToApplicationAndBankApproval" xlink:label="loc_ktos_LineOfCreditFacilityMaximumPossibleBorrowingsSubjectToApplicationAndBankApproval_4DAC4C7A1A4563FA15166134AF29DC3A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_LineOfCreditFacilityMaximumPossibleBorrowingsSubjectToApplicationAndBankApproval_4DAC4C7A1A4563FA15166134AF29DC3A" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentFixedChargeCoverageRatio" xlink:label="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_824BB4F5A811038BD6A16134AF294AEF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_824BB4F5A811038BD6A16134AF294AEF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_239019A6D4A9B36F72626134AF296E96" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_239019A6D4A9B36F72626134AF296E96" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_LineofCreditFacilityCovenantComplianceRequiredAmountofLoanRepurchased" xlink:label="loc_ktos_LineofCreditFacilityCovenantComplianceRequiredAmountofLoanRepurchased_994339331B6C6256A6066134AF2982F9" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_LineofCreditFacilityCovenantComplianceRequiredAmountofLoanRepurchased_994339331B6C6256A6066134AF2982F9" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_LineofCreditFacilityCovenantTermsCapacityofOutstandingBorrowing" xlink:label="loc_ktos_LineofCreditFacilityCovenantTermsCapacityofOutstandingBorrowing_89AE240A67C158E957FB6134AF29954A" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_LineofCreditFacilityCovenantTermsCapacityofOutstandingBorrowing_89AE240A67C158E957FB6134AF29954A" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_LineofCreditFacilityCovenantTermsPercentageofReinvestmentReserveoverOutstandingBorrowingsinExcessofCapacityofOutstandingBorrowing" xlink:label="loc_ktos_LineofCreditFacilityCovenantTermsPercentageofReinvestmentReserveoverOutstandingBorrowingsinExcessofCapacityofOutstandingBorrowing_0363CD1CD47EF296237D6134AF2994A2" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_LineofCreditFacilityCovenantTermsPercentageofReinvestmentReserveoverOutstandingBorrowingsinExcessofCapacityofOutstandingBorrowing_0363CD1CD47EF296237D6134AF2994A2" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_LineofCreditFacilityCollateralReserveAmount" xlink:label="loc_ktos_LineofCreditFacilityCollateralReserveAmount_4CE6181F87EEED9F6AFC6134AF29B051" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_LineofCreditFacilityCollateralReserveAmount_4CE6181F87EEED9F6AFC6134AF29B051" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentDurationforCollateralAdjustment" xlink:label="loc_ktos_DebtInstrumentDurationforCollateralAdjustment_EB4BFF5D2F86F8A8F1356134AF29F340" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_DebtInstrumentDurationforCollateralAdjustment_EB4BFF5D2F86F8A8F1356134AF29F340" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentCollateralAmountIncreaseDecrease" xlink:label="loc_ktos_DebtInstrumentCollateralAmountIncreaseDecrease_02FB103E1843290E4E8A6134AF2ACF92" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_DebtInstrumentCollateralAmountIncreaseDecrease_02FB103E1843290E4E8A6134AF2ACF92" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentCovenantComplianceCreditLineOutstandingExcludedFromCalculationofMinimumFixedChargeCoverageRatioAmount" xlink:label="loc_ktos_DebtInstrumentCovenantComplianceCreditLineOutstandingExcludedFromCalculationofMinimumFixedChargeCoverageRatioAmount_666B5E98E70D3913EC456134AF2A4F78" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_ktos_DebtInstrumentCovenantComplianceCreditLineOutstandingExcludedFromCalculationofMinimumFixedChargeCoverageRatioAmount_666B5E98E70D3913EC456134AF2A4F78" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_3E22EC8089B4E5E6026C6134AF2AEBC9" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_us-gaap_LineOfCredit_3E22EC8089B4E5E6026C6134AF2AEBC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_B593A338B64A2FAC16BC6134AF2A071C" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_AACBA74617AC9930445B6134AF2910CD" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_B593A338B64A2FAC16BC6134AF2A071C" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/DebtDebtAcquiredInAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_F432D3623CA60FA26DB66134AF1CDD1C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:to="loc_us-gaap_DebtInstrumentTable_F432D3623CA60FA26DB66134AF1CDD1C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_B3BCC0E1987EDDC5A2BA6134AF1CEB21" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_F432D3623CA60FA26DB66134AF1CDD1C" xlink:to="loc_us-gaap_VariableRateAxis_B3BCC0E1987EDDC5A2BA6134AF1CEB21" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_791770E72B7BF4A915EE6134AF1CA28C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_B3BCC0E1987EDDC5A2BA6134AF1CEB21" xlink:to="loc_us-gaap_VariableRateDomain_791770E72B7BF4A915EE6134AF1CA28C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_791770E72B7BF4A915EE6134AF1CA28C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_B3BCC0E1987EDDC5A2BA6134AF1CEB21" xlink:to="loc_us-gaap_VariableRateDomain_791770E72B7BF4A915EE6134AF1CA28C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3173F6962EDBA2218EC86134AF1C05BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_791770E72B7BF4A915EE6134AF1CA28C" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3173F6962EDBA2218EC86134AF1C05BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_039968FEDE7E506B6FEC6134AF1CA541" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_F432D3623CA60FA26DB66134AF1CDD1C" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_039968FEDE7E506B6FEC6134AF1CA541" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_E3D32F0CEAAE5D277A8A6134AF1CF5B1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_039968FEDE7E506B6FEC6134AF1CA541" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_E3D32F0CEAAE5D277A8A6134AF1CF5B1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_E3D32F0CEAAE5D277A8A6134AF1CF5B1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_039968FEDE7E506B6FEC6134AF1CA541" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_E3D32F0CEAAE5D277A8A6134AF1CF5B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LoansPayableMember" xlink:label="loc_us-gaap_LoansPayableMember_F18E59F3326052513A8D6134AF1C8AEE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_E3D32F0CEAAE5D277A8A6134AF1CF5B1" xlink:to="loc_us-gaap_LoansPayableMember_F18E59F3326052513A8D6134AF1C8AEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_CCBA60382D951C9C11006134AF1C352D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_CCBA60382D951C9C11006134AF1C352D" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentMaturityPeriod" xlink:label="loc_ktos_DebtInstrumentMaturityPeriod_74DF85FEF152BDFA34236134AF1CA28C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:to="loc_ktos_DebtInstrumentMaturityPeriod_74DF85FEF152BDFA34236134AF1CA28C" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_NumberofSubsidiaryOwned" xlink:label="loc_ktos_NumberofSubsidiaryOwned_C898D80F65E308DBF8676134AF1C6A07" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:to="loc_ktos_NumberofSubsidiaryOwned_C898D80F65E308DBF8676134AF1C6A07" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_4B130AF5D06A16E62EF06134AF1DE910" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:to="loc_us-gaap_LongTermDebt_4B130AF5D06A16E62EF06134AF1DE910" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_D4009C4D0165823FD3106134AF1DA286" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_D4009C4D0165823FD3106134AF1DA286" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_EBDF4362AD65F5AB38A86134AF1DCDA5" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A7F413FC9D15A42C781C6134AF1C624C" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_EBDF4362AD65F5AB38A86134AF1DCDA5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/DebtFairValueOfLongTermDebtDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/DebtIssuanceOf7SeniorSecuredNotesDue2019Details" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_D66389E7820139488E6C6134AF329384" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DebtInstrumentTable_D66389E7820139488E6C6134AF329384" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_860B6D3D0DD91F72F0EB6134AF32C24A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_D66389E7820139488E6C6134AF329384" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_860B6D3D0DD91F72F0EB6134AF32C24A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_D01378E0185DAAFD61436134AF323716_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_860B6D3D0DD91F72F0EB6134AF32C24A" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_D01378E0185DAAFD61436134AF323716_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_D01378E0185DAAFD61436134AF323716" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_860B6D3D0DD91F72F0EB6134AF32C24A" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_D01378E0185DAAFD61436134AF323716" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_0169BB22D2D0AAB85B956134AF336469" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_D01378E0185DAAFD61436134AF323716" xlink:to="loc_us-gaap_SeniorNotesMember_0169BB22D2D0AAB85B956134AF336469" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_E494C15A400F5812A01F6134AF33F45E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_D66389E7820139488E6C6134AF329384" xlink:to="loc_us-gaap_DebtInstrumentAxis_E494C15A400F5812A01F6134AF33F45E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7BDA04D1F78FA92DB5B16134AF33AE69_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_E494C15A400F5812A01F6134AF33F45E" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7BDA04D1F78FA92DB5B16134AF33AE69_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7BDA04D1F78FA92DB5B16134AF33AE69" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_E494C15A400F5812A01F6134AF33F45E" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7BDA04D1F78FA92DB5B16134AF33AE69" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_SevenPercentSeniorNotesDue2019Member" xlink:label="loc_ktos_SevenPercentSeniorNotesDue2019Member_F5C5D39DB401450C89C66134AF33765B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_7BDA04D1F78FA92DB5B16134AF33AE69" xlink:to="loc_ktos_SevenPercentSeniorNotesDue2019Member_F5C5D39DB401450C89C66134AF33765B" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_TenPercentSeniorNotesDueJune2017Member" xlink:label="loc_ktos_TenPercentSeniorNotesDueJune2017Member_3903B2D67DB8003DD5626134AF33FF58" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_7BDA04D1F78FA92DB5B16134AF33AE69" xlink:to="loc_ktos_TenPercentSeniorNotesDueJune2017Member_3903B2D67DB8003DD5626134AF33FF58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_D009FADEF5C64290DDE26134AF33876B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_D66389E7820139488E6C6134AF329384" xlink:to="loc_us-gaap_CreditFacilityAxis_D009FADEF5C64290DDE26134AF33876B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_CFEF765FE7DD400A6FC46134AF33606E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_D009FADEF5C64290DDE26134AF33876B" xlink:to="loc_us-gaap_CreditFacilityDomain_CFEF765FE7DD400A6FC46134AF33606E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_CFEF765FE7DD400A6FC46134AF33606E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_D009FADEF5C64290DDE26134AF33876B" xlink:to="loc_us-gaap_CreditFacilityDomain_CFEF765FE7DD400A6FC46134AF33606E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_C18BC9E35F84E238F6AA6134AF33982F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_CFEF765FE7DD400A6FC46134AF33606E" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_C18BC9E35F84E238F6AA6134AF33982F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_738B9109830BAAFD23FC6134AF333848" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_D66389E7820139488E6C6134AF329384" xlink:to="loc_us-gaap_StatementScenarioAxis_738B9109830BAAFD23FC6134AF333848" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_5C6D65621A70C8140EC76134AF333493_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_738B9109830BAAFD23FC6134AF333848" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_5C6D65621A70C8140EC76134AF333493_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_5C6D65621A70C8140EC76134AF333493" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_738B9109830BAAFD23FC6134AF333848" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_5C6D65621A70C8140EC76134AF333493" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_RedemptionPeriodThreeMember" xlink:label="loc_ktos_RedemptionPeriodThreeMember_7863AFE55F455A570AD46134AF33D968" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_5C6D65621A70C8140EC76134AF333493" xlink:to="loc_ktos_RedemptionPeriodThreeMember_7863AFE55F455A570AD46134AF33D968" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_RedemptionPeriodFourMember" xlink:label="loc_ktos_RedemptionPeriodFourMember_F2EC4501A629110B2FE46134AF334D83" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_5C6D65621A70C8140EC76134AF333493" xlink:to="loc_ktos_RedemptionPeriodFourMember_F2EC4501A629110B2FE46134AF334D83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_120334E27285FB75FA566134AF344FCD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_120334E27285FB75FA566134AF344FCD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_883D133300DD5F4FB99F6134AF34943A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_883D133300DD5F4FB99F6134AF34943A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_D77723D3D9AAB47013C06134AF34C79E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_D77723D3D9AAB47013C06134AF34C79E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_B4D1A144C04CB8A331AE6134AF34D87F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_B4D1A144C04CB8A331AE6134AF34D87F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DeferredFinanceCostsGross" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_134AA663AD83C1E6CC126184D517B052" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_134AA663AD83C1E6CC126184D517B052" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_C01C44B5D6C010AA57E36134AF34BEE7" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_C01C44B5D6C010AA57E36134AF34BEE7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentRepurchaseAmount" xlink:label="loc_us-gaap_DebtInstrumentRepurchaseAmount_235FE4B4A92509D833AA6134AF348E26" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DebtInstrumentRepurchaseAmount_235FE4B4A92509D833AA6134AF348E26" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentEarlyTerminationFee" xlink:label="loc_ktos_DebtInstrumentEarlyTerminationFee_053DABAE264FA0A54A9B6134AF34C467" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_ktos_DebtInstrumentEarlyTerminationFee_053DABAE264FA0A54A9B6134AF34C467" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_42EE8F499B2D770C78976134AF3421FF" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_42EE8F499B2D770C78976134AF3421FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentUnamortizedPremium" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedPremium_BE80EFD6231959A57F146134AF34B3C9" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedPremium_BE80EFD6231959A57F146134AF34B3C9" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentEscrowInterestAccrued" xlink:label="loc_ktos_DebtInstrumentEscrowInterestAccrued_32CA3FE008C1F371D2706134AF349821" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_ktos_DebtInstrumentEscrowInterestAccrued_32CA3FE008C1F371D2706134AF349821" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_3D63D7D72B670916A3156134AF35B9CB" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_3D63D7D72B670916A3156134AF35B9CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_670FC2093B017439194E6134AF355C4E" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_670FC2093B017439194E6134AF355C4E" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentFixedChargeCoverageRatio" xlink:label="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_F9A2F53E55378C2684B66134AF356386" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_F9A2F53E55378C2684B66134AF356386" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentRedemptionAmountAsPercentageOfAggregatePrincipalAmount" xlink:label="loc_ktos_DebtInstrumentRedemptionAmountAsPercentageOfAggregatePrincipalAmount_FF8F1D2583F78AB4C32F6134AF354DDD" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_ktos_DebtInstrumentRedemptionAmountAsPercentageOfAggregatePrincipalAmount_FF8F1D2583F78AB4C32F6134AF354DDD" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_DebtInstrumentDurationFollowingSaleRequiredtoRepurchaseLoanWithUnusedProceeds" xlink:label="loc_ktos_DebtInstrumentDurationFollowingSaleRequiredtoRepurchaseLoanWithUnusedProceeds_0AF42A90627CF46CC53D6134AF3551E6" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_ktos_DebtInstrumentDurationFollowingSaleRequiredtoRepurchaseLoanWithUnusedProceeds_0AF42A90627CF46CC53D6134AF3551E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_139777FE38E62CA5B6EF6134AF35A1B9" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_LineOfCredit_139777FE38E62CA5B6EF6134AF35A1B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_355D2343060B89B2449861B2A73439A7" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_355D2343060B89B2449861B2A73439A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LegalFees" xlink:label="loc_us-gaap_LegalFees_CD6A0DBC70B0C72C9B196134AF35E508" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_LegalFees_CD6A0DBC70B0C72C9B196134AF35E508" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost_984DAFAD73AA02A16E296134AF3529BC" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost_984DAFAD73AA02A16E296134AF3529BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SeniorNotes" xlink:label="loc_us-gaap_SeniorNotes_2E0D4C7B1B11D5339E4E6134AF354E9A" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_468830D8A741278843696134AF34A1BB" xlink:to="loc_us-gaap_SeniorNotes_2E0D4C7B1B11D5339E4E6134AF354E9A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/DebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsGoodwillDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_C456134C359A6CE4AF746134AF9D8205" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_2031AD3B0582A69169E96134AF9D8A8E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_C456134C359A6CE4AF746134AF9D8205" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_2031AD3B0582A69169E96134AF9D8A8E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_C669EED06CE2F21881306134AF9DC3A7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_2031AD3B0582A69169E96134AF9D8A8E" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_C669EED06CE2F21881306134AF9DC3A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_2B89B77A2C6E48DFF24D6134AF9DCD0F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_C669EED06CE2F21881306134AF9DC3A7" xlink:to="loc_us-gaap_SegmentDomain_2B89B77A2C6E48DFF24D6134AF9DCD0F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_2B89B77A2C6E48DFF24D6134AF9DCD0F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_C669EED06CE2F21881306134AF9DC3A7" xlink:to="loc_us-gaap_SegmentDomain_2B89B77A2C6E48DFF24D6134AF9DCD0F" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_A780A820E73951432CCE6134AF9DA000" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2B89B77A2C6E48DFF24D6134AF9DCD0F" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_A780A820E73951432CCE6134AF9DA000" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_KratosGovernmentSolutionsMember" xlink:label="loc_ktos_KratosGovernmentSolutionsMember_004FABB76C9E0F9E5F2E6134AF9D2786" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2B89B77A2C6E48DFF24D6134AF9DCD0F" xlink:to="loc_ktos_KratosGovernmentSolutionsMember_004FABB76C9E0F9E5F2E6134AF9D2786" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_KratosUnmannedSystemsMember" xlink:label="loc_ktos_KratosUnmannedSystemsMember_A0F8884C413B0C122B656134AF9D5E3A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2B89B77A2C6E48DFF24D6134AF9DCD0F" xlink:to="loc_ktos_KratosUnmannedSystemsMember_A0F8884C413B0C122B656134AF9D5E3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GoodwillGross" xlink:label="loc_us-gaap_GoodwillGross_D31D429A4A53F3848B8A6134AF9DA838" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_C456134C359A6CE4AF746134AF9D8205" xlink:to="loc_us-gaap_GoodwillGross_D31D429A4A53F3848B8A6134AF9DA838" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_2C4122BEBAEDD7A14A0B6134AF9E948F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_C456134C359A6CE4AF746134AF9D8205" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_2C4122BEBAEDD7A14A0B6134AF9E948F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_8015D6B5E04601F5CC016134AF9E8BA3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_C456134C359A6CE4AF746134AF9D8205" xlink:to="loc_us-gaap_Goodwill_8015D6B5E04601F5CC016134AF9E8BA3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsPurchasedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0577E236907ECEB46AA86134AF8D5308" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_F13204029EF1B09B4EF86134AF87E5D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0577E236907ECEB46AA86134AF8D5308" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_F13204029EF1B09B4EF86134AF87E5D0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_35755A31DD0D7E4080206134AF876A7D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_F13204029EF1B09B4EF86134AF87E5D0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_35755A31DD0D7E4080206134AF876A7D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_35755A31DD0D7E4080206134AF876A7D" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_35755A31DD0D7E4080206134AF876A7D" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_A8FA1071936FE7691AEF6134AF870CC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082" xlink:to="loc_us-gaap_CustomerRelationshipsMember_A8FA1071936FE7691AEF6134AF870CC1" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_ContractsAndBacklogMember" xlink:label="loc_ktos_ContractsAndBacklogMember_60490BFDB1F9AFA745E96134AF8828D9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082" xlink:to="loc_ktos_ContractsAndBacklogMember_60490BFDB1F9AFA745E96134AF8828D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_7BE3545744A38CDA4EDF6134AF88553E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_7BE3545744A38CDA4EDF6134AF88553E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_7D40F4A351AA549B2F976134AF8864B9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ED750A4C62F478B13DAC6134AF870082" xlink:to="loc_us-gaap_TradeNamesMember_7D40F4A351AA549B2F976134AF8864B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_C1B7E63D8E27B989AAB16134AF8896C9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_F13204029EF1B09B4EF86134AF87E5D0" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_C1B7E63D8E27B989AAB16134AF8896C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_F95C22B0945CF840FEE16134AF881E45_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_C1B7E63D8E27B989AAB16134AF8896C9" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_F95C22B0945CF840FEE16134AF881E45_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_F95C22B0945CF840FEE16134AF881E45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_C1B7E63D8E27B989AAB16134AF8896C9" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_F95C22B0945CF840FEE16134AF881E45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_AC1A54E14B5E5E97B55A6134AF8D6CA6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_F95C22B0945CF840FEE16134AF881E45" xlink:to="loc_us-gaap_TradeNamesMember_AC1A54E14B5E5E97B55A6134AF8D6CA6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_5592C4AC102446F6E71B6134AF8D2387" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0577E236907ECEB46AA86134AF8D5308" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_5592C4AC102446F6E71B6134AF8D2387" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_E83E5E244B61194DCD256134AF8DFDD9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_5592C4AC102446F6E71B6134AF8D2387" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_E83E5E244B61194DCD256134AF8DFDD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_0DF390200CC5A1FF4E306134AF8DA73B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_5592C4AC102446F6E71B6134AF8D2387" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_0DF390200CC5A1FF4E306134AF8DA73B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_50D5D34CF354888A92796134AF8EC7DC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_5592C4AC102446F6E71B6134AF8D2387" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_50D5D34CF354888A92796134AF8EC7DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_ED5372364F73C6A69C696134AF8E4F07" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0577E236907ECEB46AA86134AF8D5308" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_ED5372364F73C6A69C696134AF8E4F07" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_IntangibleAssetsExcludingGoodwillGross" xlink:label="loc_ktos_IntangibleAssetsExcludingGoodwillGross_0E264CB011EB984B02316134AF8E9967" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0577E236907ECEB46AA86134AF8D5308" xlink:to="loc_ktos_IntangibleAssetsExcludingGoodwillGross_0E264CB011EB984B02316134AF8E9967" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_19A700F7A3AC0310D2066134AF8EF9CB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0577E236907ECEB46AA86134AF8D5308" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_19A700F7A3AC0310D2066134AF8EF9CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_E29B1161AA98D2D93A346134AF8E90C2" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0577E236907ECEB46AA86134AF8D5308" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_E29B1161AA98D2D93A346134AF8E90C2" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/IncomeTaxesIncomeTaxProvisionReconciliationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/IncomeTaxesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/InventoriedCosts" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/InventoriedCostsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/InventoriedCostsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/NetLossPerCommonShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/NetLossPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C78372F21435470AA0856134AF4B427F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_225B99AEE0AC7CA3A3136134AF4AE4C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C78372F21435470AA0856134AF4B427F" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_225B99AEE0AC7CA3A3136134AF4AE4C0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_801309186A539E089B756134AF4A1CB5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_225B99AEE0AC7CA3A3136134AF4AE4C0" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_801309186A539E089B756134AF4A1CB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_7F458FD2BAF7C417A3676134AF4BED72_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_801309186A539E089B756134AF4A1CB5" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_7F458FD2BAF7C417A3676134AF4BED72_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_7F458FD2BAF7C417A3676134AF4BED72" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_801309186A539E089B756134AF4A1CB5" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_7F458FD2BAF7C417A3676134AF4BED72" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_StockOptionsAndStockAwardsMember" xlink:label="loc_ktos_StockOptionsAndStockAwardsMember_0AE0DCB3D340FBE223A86134AF4B9746" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_7F458FD2BAF7C417A3676134AF4BED72" xlink:to="loc_ktos_StockOptionsAndStockAwardsMember_0AE0DCB3D340FBE223A86134AF4B9746" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_21CB13D99AEDD82C8C1E6134AF4B1895" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C78372F21435470AA0856134AF4B427F" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_21CB13D99AEDD82C8C1E6134AF4B1895" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SegmentInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SegmentInformationAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_379E0B12F21A7B5A96416134AF1001F4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_84A7055A8E99099B79416134AF0F918C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_379E0B12F21A7B5A96416134AF1001F4" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_84A7055A8E99099B79416134AF0F918C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_61E2EAFDCC48F589121F6134AF0F2863" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_84A7055A8E99099B79416134AF0F918C" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_61E2EAFDCC48F589121F6134AF0F2863" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_C04A0CA76DE10111AED26134AF0FD8E4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_61E2EAFDCC48F589121F6134AF0F2863" xlink:to="loc_us-gaap_SegmentDomain_C04A0CA76DE10111AED26134AF0FD8E4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_C04A0CA76DE10111AED26134AF0FD8E4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_61E2EAFDCC48F589121F6134AF0F2863" xlink:to="loc_us-gaap_SegmentDomain_C04A0CA76DE10111AED26134AF0FD8E4" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_2FEB799B0301EBD048386134AF0F5A93" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_C04A0CA76DE10111AED26134AF0FD8E4" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_2FEB799B0301EBD048386134AF0F5A93" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_KratosGovernmentSolutionsMember" xlink:label="loc_ktos_KratosGovernmentSolutionsMember_2AC9EE1F7BEF454AE12B6134AF1073F2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_C04A0CA76DE10111AED26134AF0FD8E4" xlink:to="loc_ktos_KratosGovernmentSolutionsMember_2AC9EE1F7BEF454AE12B6134AF1073F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_01AD47E035B123A6C5236134AF10B94F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_84A7055A8E99099B79416134AF0F918C" xlink:to="loc_us-gaap_LitigationStatusAxis_01AD47E035B123A6C5236134AF10B94F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_26BD9F28EDF843AD6B946134AF10367C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_01AD47E035B123A6C5236134AF10B94F" xlink:to="loc_us-gaap_LitigationStatusDomain_26BD9F28EDF843AD6B946134AF10367C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_26BD9F28EDF843AD6B946134AF10367C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_01AD47E035B123A6C5236134AF10B94F" xlink:to="loc_us-gaap_LitigationStatusDomain_26BD9F28EDF843AD6B946134AF10367C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SettledLitigationMember" xlink:label="loc_us-gaap_SettledLitigationMember_13BB3C889183646BF5C56134AF10424D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_26BD9F28EDF843AD6B946134AF10367C" xlink:to="loc_us-gaap_SettledLitigationMember_13BB3C889183646BF5C56134AF10424D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PublicUtilitiesInventoryAxis" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_149F9F738000A9CD01186134AF1011DA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_84A7055A8E99099B79416134AF0F918C" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_149F9F738000A9CD01186134AF1011DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_419AA7DD4E26879035EC6134AF104D97_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_149F9F738000A9CD01186134AF1011DA" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_419AA7DD4E26879035EC6134AF104D97_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_419AA7DD4E26879035EC6134AF104D97" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_149F9F738000A9CD01186134AF1011DA" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_419AA7DD4E26879035EC6134AF104D97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InventoriesMember" xlink:label="loc_us-gaap_InventoriesMember_D405762C5E9C03480CC46134AF100C0D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_419AA7DD4E26879035EC6134AF104D97" xlink:to="loc_us-gaap_InventoriesMember_D405762C5E9C03480CC46134AF100C0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_0BA766C5DDBE76AABE2161422D3EA9DA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_379E0B12F21A7B5A96416134AF1001F4" xlink:to="loc_us-gaap_NumberOfReportableSegments_0BA766C5DDBE76AABE2161422D3EA9DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LitigationSettlementExpense" xlink:label="loc_us-gaap_LitigationSettlementExpense_48F24995F21EF103B0746134AF10E6F3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_379E0B12F21A7B5A96416134AF1001F4" xlink:to="loc_us-gaap_LitigationSettlementExpense_48F24995F21EF103B0746134AF10E6F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaap_AssetImpairmentCharges_2C4EACCBC0D7FF4E105D6134AF101402" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_379E0B12F21A7B5A96416134AF1001F4" xlink:to="loc_us-gaap_AssetImpairmentCharges_2C4EACCBC0D7FF4E105D6134AF101402" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SegmentInformationScheduleOfSegmentRevenuesDepreciationAndAmortizationAndOperatingLossDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_C76723CEC65CAB5C18A76134AF0A6476" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8160817F411233ABE3366134AF0929C7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_C76723CEC65CAB5C18A76134AF0A6476" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8160817F411233ABE3366134AF0929C7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_30919B812F359E00635D6134AF09B58F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8160817F411233ABE3366134AF0929C7" xlink:to="loc_us-gaap_ConsolidationItemsAxis_30919B812F359E00635D6134AF09B58F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_67C4FE3896B781A10AB16134AF09E352_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_30919B812F359E00635D6134AF09B58F" xlink:to="loc_us-gaap_ConsolidationItemsDomain_67C4FE3896B781A10AB16134AF09E352_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_67C4FE3896B781A10AB16134AF09E352" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_30919B812F359E00635D6134AF09B58F" xlink:to="loc_us-gaap_ConsolidationItemsDomain_67C4FE3896B781A10AB16134AF09E352" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_FAA36B08283636E625E16134AF096A58" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_67C4FE3896B781A10AB16134AF09E352" xlink:to="loc_us-gaap_OperatingSegmentsMember_FAA36B08283636E625E16134AF096A58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_77AE40BDC0ED09DB16B06134AF09378B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_67C4FE3896B781A10AB16134AF09E352" xlink:to="loc_us-gaap_CorporateNonSegmentMember_77AE40BDC0ED09DB16B06134AF09378B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8858C91F0AFB524BD6BB6134AF0AF9C6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8160817F411233ABE3366134AF0929C7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8858C91F0AFB524BD6BB6134AF0AF9C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_DA8F607B84FBF395B1006134AF0AFE43_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8858C91F0AFB524BD6BB6134AF0AF9C6" xlink:to="loc_us-gaap_SegmentDomain_DA8F607B84FBF395B1006134AF0AFE43_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_DA8F607B84FBF395B1006134AF0AFE43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8858C91F0AFB524BD6BB6134AF0AF9C6" xlink:to="loc_us-gaap_SegmentDomain_DA8F607B84FBF395B1006134AF0AFE43" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_KratosGovernmentSolutionsMember" xlink:label="loc_ktos_KratosGovernmentSolutionsMember_D9EE1A5A714E957810166134AF0A25A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_DA8F607B84FBF395B1006134AF0AFE43" xlink:to="loc_ktos_KratosGovernmentSolutionsMember_D9EE1A5A714E957810166134AF0A25A3" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_0F27F094A7FED941767A6134AF0AB5C0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_DA8F607B84FBF395B1006134AF0AFE43" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_0F27F094A7FED941767A6134AF0AB5C0" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_KratosUnmannedSystemsMember" xlink:label="loc_ktos_KratosUnmannedSystemsMember_ABDB16A0D3E2D9D6AA126134AF0A3259" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_DA8F607B84FBF395B1006134AF0AFE43" xlink:to="loc_ktos_KratosUnmannedSystemsMember_ABDB16A0D3E2D9D6AA126134AF0A3259" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_9A407631C970471513B66134AF0AE3B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_C76723CEC65CAB5C18A76134AF0A6476" xlink:to="loc_us-gaap_RevenuesAbstract_9A407631C970471513B66134AF0AE3B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueServicesNet" xlink:label="loc_us-gaap_SalesRevenueServicesNet_0F8A74C620301044B6726134AF0A719F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_9A407631C970471513B66134AF0AE3B4" xlink:to="loc_us-gaap_SalesRevenueServicesNet_0F8A74C620301044B6726134AF0A719F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:label="loc_us-gaap_SalesRevenueGoodsNet_7EDC4F2DDFD5E4FA83FB6134AF0AE98A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_9A407631C970471513B66134AF0AE3B4" xlink:to="loc_us-gaap_SalesRevenueGoodsNet_7EDC4F2DDFD5E4FA83FB6134AF0AE98A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_EBEB3928933B80A93B526134AF0A61E7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_9A407631C970471513B66134AF0AE3B4" xlink:to="loc_us-gaap_SalesRevenueNet_EBEB3928933B80A93B526134AF0A61E7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract_B95CD0AEDFD4A32638456134AF0AFA03" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_C76723CEC65CAB5C18A76134AF0A6476" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract_B95CD0AEDFD4A32638456134AF0AFA03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_C6CC0E440FC973A5610B6134AF0A17A1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract_B95CD0AEDFD4A32638456134AF0AFA03" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_C6CC0E440FC973A5610B6134AF0A17A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingIncomeLossAbstract" xlink:label="loc_us-gaap_OperatingIncomeLossAbstract_D20D6F3772B348EEA9C36134AF0A0FB5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_C76723CEC65CAB5C18A76134AF0A6476" xlink:to="loc_us-gaap_OperatingIncomeLossAbstract_D20D6F3772B348EEA9C36134AF0A0FB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_7BDDF87BBEDBF46ABF076134AF0BB113" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingIncomeLossAbstract_D20D6F3772B348EEA9C36134AF0A0FB5" xlink:to="loc_us-gaap_OperatingIncomeLoss_7BDDF87BBEDBF46ABF076134AF0BB113" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SegmentInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SignificantCustomers" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SignificantCustomersDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_C0C0500ADD5CB5D2821D6134AF0265CB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_896B7B1B58212D879DA56134AF014FE8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_C0C0500ADD5CB5D2821D6134AF0265CB" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_896B7B1B58212D879DA56134AF014FE8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_C96782AA2EB05CE22CB56134AF01715C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_896B7B1B58212D879DA56134AF014FE8" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_C96782AA2EB05CE22CB56134AF01715C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_3EBC0CD971E2CADA7A276134AF018960_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_C96782AA2EB05CE22CB56134AF01715C" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_3EBC0CD971E2CADA7A276134AF018960_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_3EBC0CD971E2CADA7A276134AF018960" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_C96782AA2EB05CE22CB56134AF01715C" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_3EBC0CD971E2CADA7A276134AF018960" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_1DB41D5E47AA0A20702A6134AF016628" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_3EBC0CD971E2CADA7A276134AF018960" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_1DB41D5E47AA0A20702A6134AF016628" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_12D19294CC9F821CB1966134AF01C705" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_896B7B1B58212D879DA56134AF014FE8" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_12D19294CC9F821CB1966134AF01C705" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_97E82CD0A5A2E2C3899D6134AF017E00_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_12D19294CC9F821CB1966134AF01C705" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_97E82CD0A5A2E2C3899D6134AF017E00_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_97E82CD0A5A2E2C3899D6134AF017E00" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_12D19294CC9F821CB1966134AF01C705" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_97E82CD0A5A2E2C3899D6134AF017E00" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_F18687D04674D4BEED446134AF017FAD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_97E82CD0A5A2E2C3899D6134AF017E00" xlink:to="loc_us-gaap_SalesRevenueNetMember_F18687D04674D4BEED446134AF017FAD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:label="loc_us-gaap_MajorCustomersAxis_4CB9191525836A552D396134AF01E17E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_896B7B1B58212D879DA56134AF014FE8" xlink:to="loc_us-gaap_MajorCustomersAxis_4CB9191525836A552D396134AF01E17E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_9742AE83285C6EAE84B96134AF0178E0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorCustomersAxis_4CB9191525836A552D396134AF01E17E" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_9742AE83285C6EAE84B96134AF0178E0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_9742AE83285C6EAE84B96134AF0178E0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorCustomersAxis_4CB9191525836A552D396134AF01E17E" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_9742AE83285C6EAE84B96134AF0178E0" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_USGovernmentMember" xlink:label="loc_ktos_USGovernmentMember_E9DF6AC3E9406CE084596134AF02C691" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_9742AE83285C6EAE84B96134AF0178E0" xlink:to="loc_ktos_USGovernmentMember_E9DF6AC3E9406CE084596134AF02C691" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_60BC43E78CC9314544186134AF027EAD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_C0C0500ADD5CB5D2821D6134AF0265CB" xlink:to="loc_us-gaap_Revenues_60BC43E78CC9314544186134AF027EAD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_9A6C7F4D0AF14F3571CD6134AF0283DE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_C0C0500ADD5CB5D2821D6134AF0265CB" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_9A6C7F4D0AF14F3571CD6134AF0283DE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/StockholdersEquity" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/StockholdersEquityAccumulatedOtherComprehensiveLossDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_26FFC38E569A1D1654186134AF54A22A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_F87909697DF7423BC6A96134AF5387E3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_26FFC38E569A1D1654186134AF54A22A" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_F87909697DF7423BC6A96134AF5387E3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_041636613EF63E4C8C9A6134AF540A19" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_F87909697DF7423BC6A96134AF5387E3" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_041636613EF63E4C8C9A6134AF540A19" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_F56BEB00857C721A04646134AF54162C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_041636613EF63E4C8C9A6134AF540A19" xlink:to="loc_us-gaap_EquityComponentDomain_F56BEB00857C721A04646134AF54162C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_F56BEB00857C721A04646134AF54162C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_041636613EF63E4C8C9A6134AF540A19" xlink:to="loc_us-gaap_EquityComponentDomain_F56BEB00857C721A04646134AF54162C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_2E4C62BF1555C7F6405B6134AF54C7CA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_F56BEB00857C721A04646134AF54162C" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_2E4C62BF1555C7F6405B6134AF54C7CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_81F3520EDF45B4D1896A6134AF544AF4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_F56BEB00857C721A04646134AF54162C" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_81F3520EDF45B4D1896A6134AF544AF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_042A7CB0FAFEFC24C6606134AF545391" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_26FFC38E569A1D1654186134AF54A22A" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_042A7CB0FAFEFC24C6606134AF545391" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_AEB590116C7E2D5D85036134AF544905" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_26FFC38E569A1D1654186134AF54A22A" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_AEB590116C7E2D5D85036134AF544905" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/StockholdersEquityRollforwardOfCommonStockOutstandingDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/StockholdersEquitySummaryOfChangesInStockholdersEquityDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/StockholdersEquityTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D0E2DB6072935CEF9556134B01BA78D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_A5BD8D510C5126B703276134B0158569" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D0E2DB6072935CEF9556134B01BA78D" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_A5BD8D510C5126B703276134B0158569" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_59B59EBD017B51FC7A886134B01503AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_A5BD8D510C5126B703276134B0158569" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_59B59EBD017B51FC7A886134B01503AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_B7CB8C03CB16A8DAB79A6134B015761A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_59B59EBD017B51FC7A886134B01503AF" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_B7CB8C03CB16A8DAB79A6134B015761A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_B7CB8C03CB16A8DAB79A6134B015761A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_59B59EBD017B51FC7A886134B01503AF" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_B7CB8C03CB16A8DAB79A6134B015761A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CounterpartyNameAxis" xlink:label="loc_us-gaap_CounterpartyNameAxis_BC588793740105C884F26134B0156C5B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_A5BD8D510C5126B703276134B0158569" xlink:to="loc_us-gaap_CounterpartyNameAxis_BC588793740105C884F26134B0156C5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_8B9B4B18A898136E3CA46134B0156AD9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CounterpartyNameAxis_BC588793740105C884F26134B0156C5B" xlink:to="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_8B9B4B18A898136E3CA46134B0156AD9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_8B9B4B18A898136E3CA46134B0156AD9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CounterpartyNameAxis_BC588793740105C884F26134B0156C5B" xlink:to="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_8B9B4B18A898136E3CA46134B0156AD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_77D9E20BF9031D53B6A06134B01A84C7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_A5BD8D510C5126B703276134B0158569" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_77D9E20BF9031D53B6A06134B01A84C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6A7301AFFDA6B202B9FF6134B01A47CE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_77D9E20BF9031D53B6A06134B01A84C7" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6A7301AFFDA6B202B9FF6134B01A47CE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6A7301AFFDA6B202B9FF6134B01A47CE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_77D9E20BF9031D53B6A06134B01A84C7" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6A7301AFFDA6B202B9FF6134B01A47CE" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_HerleyIndustriesIncMember" xlink:label="loc_ktos_HerleyIndustriesIncMember_18A421EE3D498A003A5C6134B01A7821" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6A7301AFFDA6B202B9FF6134B01A47CE" xlink:to="loc_ktos_HerleyIndustriesIncMember_18A421EE3D498A003A5C6134B01A7821" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_37639932529F1D9AB3396134B01BFBEB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_A5BD8D510C5126B703276134B0158569" xlink:to="loc_us-gaap_RangeAxis_37639932529F1D9AB3396134B01BFBEB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_755FD13565D98E8C96EE6134B01BDEF3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_37639932529F1D9AB3396134B01BFBEB" xlink:to="loc_us-gaap_RangeMember_755FD13565D98E8C96EE6134B01BDEF3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_755FD13565D98E8C96EE6134B01BDEF3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_37639932529F1D9AB3396134B01BFBEB" xlink:to="loc_us-gaap_RangeMember_755FD13565D98E8C96EE6134B01BDEF3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_EE2CBBEF8D93F7A75BF26134B01BF58B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_755FD13565D98E8C96EE6134B01BDEF3" xlink:to="loc_us-gaap_MinimumMember_EE2CBBEF8D93F7A75BF26134B01BF58B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_38E1261BCAA26C7F704E6134B01B401A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_755FD13565D98E8C96EE6134B01BDEF3" xlink:to="loc_us-gaap_MaximumMember_38E1261BCAA26C7F704E6134B01B401A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_6978EE281784E0D6E94A6134B01B3700" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D0E2DB6072935CEF9556134B01BA78D" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_6978EE281784E0D6E94A6134B01B3700" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_FiscalYearDuration" xlink:label="loc_ktos_FiscalYearDuration_E8FD6D5734D4E67B0B0F6134B01B3203" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D0E2DB6072935CEF9556134B01BA78D" xlink:to="loc_ktos_FiscalYearDuration_E8FD6D5734D4E67B0B0F6134B01B3203" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170625.xsd#ktos_FiscalYearToDateDuration" xlink:label="loc_ktos_FiscalYearToDateDuration_030DEDC46B05D2783BA96134B01B498F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D0E2DB6072935CEF9556134B01BA78D" xlink:to="loc_ktos_FiscalYearToDateDuration_030DEDC46B05D2783BA96134B01B498F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
</link:linkbase>
