<?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-20170326.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CommitmentsAndContingenciesDetails" xlink:href="ktos-20170326.xsd#CommitmentsAndContingenciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:href="ktos-20170326.xsd#CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:href="ktos-20170326.xsd#CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:href="ktos-20170326.xsd#CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveLossUnaudited" xlink:href="ktos-20170326.xsd#CondensedConsolidatedStatementsOfOperationsAndComprehensiveLossUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatements" xlink:href="ktos-20170326.xsd#CondensedConsolidatingFinancialStatements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsBalanceSheetDetails" xlink:href="ktos-20170326.xsd#CondensedConsolidatingFinancialStatementsBalanceSheetDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsCondensedConsolidatingFinancialStatementsTables" xlink:href="ktos-20170326.xsd#CondensedConsolidatingFinancialStatementsCondensedConsolidatingFinancialStatementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsStatementOfCashFlowsDetails" xlink:href="ktos-20170326.xsd#CondensedConsolidatingFinancialStatementsStatementOfCashFlowsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsStatementOfOperationsAndComprehensiveIncomeLossDetails" xlink:href="ktos-20170326.xsd#CondensedConsolidatingFinancialStatementsStatementOfOperationsAndComprehensiveIncomeLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/Debt" xlink:href="ktos-20170326.xsd#Debt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/Debt1100MillionCreditAgreementDetails" xlink:href="ktos-20170326.xsd#Debt1100MillionCreditAgreementDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtDebtAcquiredInAcquisitionDetails" xlink:href="ktos-20170326.xsd#DebtDebtAcquiredInAcquisitionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtFairValueOfLongTermDebtDetails" xlink:href="ktos-20170326.xsd#DebtFairValueOfLongTermDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtIssuanceOf7SeniorSecuredNotesDue2019Details" xlink:href="ktos-20170326.xsd#DebtIssuanceOf7SeniorSecuredNotesDue2019Details" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DebtTables" xlink:href="ktos-20170326.xsd#DebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/DocumentAndEntityInformation" xlink:href="ktos-20170326.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssets" xlink:href="ktos-20170326.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsGoodwillDetails" xlink:href="ktos-20170326.xsd#GoodwillAndIntangibleAssetsGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsPurchasedIntangibleAssetsDetails" xlink:href="ktos-20170326.xsd#GoodwillAndIntangibleAssetsPurchasedIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="ktos-20170326.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxes" xlink:href="ktos-20170326.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxesAdditionalInformationDetails" xlink:href="ktos-20170326.xsd#IncomeTaxesAdditionalInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxesIncomeTaxProvisionReconciliationDetails" xlink:href="ktos-20170326.xsd#IncomeTaxesIncomeTaxProvisionReconciliationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/IncomeTaxesTables" xlink:href="ktos-20170326.xsd#IncomeTaxesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/InventoriedCosts" xlink:href="ktos-20170326.xsd#InventoriedCosts" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/InventoriedCostsDetails" xlink:href="ktos-20170326.xsd#InventoriedCostsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/InventoriedCostsTables" xlink:href="ktos-20170326.xsd#InventoriedCostsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/NetLossPerCommonShare" xlink:href="ktos-20170326.xsd#NetLossPerCommonShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/NetLossPerCommonShareDetails" xlink:href="ktos-20170326.xsd#NetLossPerCommonShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformation" xlink:href="ktos-20170326.xsd#SegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformationAdditionalInformationDetails" xlink:href="ktos-20170326.xsd#SegmentInformationAdditionalInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformationScheduleOfSegmentRevenuesDepreciationAndAmortizationAndOperatingLossDetails" xlink:href="ktos-20170326.xsd#SegmentInformationScheduleOfSegmentRevenuesDepreciationAndAmortizationAndOperatingLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SegmentInformationTables" xlink:href="ktos-20170326.xsd#SegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SignificantCustomers" xlink:href="ktos-20170326.xsd#SignificantCustomers" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SignificantCustomersDetails" xlink:href="ktos-20170326.xsd#SignificantCustomersDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquity" xlink:href="ktos-20170326.xsd#StockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquityAccumulatedOtherComprehensiveLossDetails" xlink:href="ktos-20170326.xsd#StockholdersEquityAccumulatedOtherComprehensiveLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquityRollforwardOfCommonStockOutstandingDetails" xlink:href="ktos-20170326.xsd#StockholdersEquityRollforwardOfCommonStockOutstandingDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquitySummaryOfChangesInStockholdersEquityDetails" xlink:href="ktos-20170326.xsd#StockholdersEquitySummaryOfChangesInStockholdersEquityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/StockholdersEquityTables" xlink:href="ktos-20170326.xsd#StockholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="ktos-20170326.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:href="ktos-20170326.xsd#SummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="ktos-20170326.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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_E4D93115A6B0C18A9899207664E68B59" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_0F852D0C9EF5F845B91C207664E54BC3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_E4D93115A6B0C18A9899207664E68B59" xlink:to="loc_us-gaap_LossContingenciesTable_0F852D0C9EF5F845B91C207664E54BC3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_B79EBB55FB404BC25801207664E592AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_0F852D0C9EF5F845B91C207664E54BC3" xlink:to="loc_us-gaap_LitigationStatusAxis_B79EBB55FB404BC25801207664E592AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_29624455C240B440C35A207664E57D9A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_B79EBB55FB404BC25801207664E592AF" xlink:to="loc_us-gaap_LitigationStatusDomain_29624455C240B440C35A207664E57D9A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_29624455C240B440C35A207664E57D9A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_B79EBB55FB404BC25801207664E592AF" xlink:to="loc_us-gaap_LitigationStatusDomain_29624455C240B440C35A207664E57D9A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SettledLitigationMember" xlink:label="loc_us-gaap_SettledLitigationMember_A2FA680E508199D56485207664E5DAF8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_29624455C240B440C35A207664E57D9A" xlink:to="loc_us-gaap_SettledLitigationMember_A2FA680E508199D56485207664E5DAF8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_ABF905AC9FEBDBC1FBA0207664E63C8D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_0F852D0C9EF5F845B91C207664E54BC3" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_ABF905AC9FEBDBC1FBA0207664E63C8D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_07EEABED0451EF2C48A4207664E69A57_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_ABF905AC9FEBDBC1FBA0207664E63C8D" xlink:to="loc_us-gaap_SegmentDomain_07EEABED0451EF2C48A4207664E69A57_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_07EEABED0451EF2C48A4207664E69A57" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_ABF905AC9FEBDBC1FBA0207664E63C8D" xlink:to="loc_us-gaap_SegmentDomain_07EEABED0451EF2C48A4207664E69A57" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_40E8C5517B67EE1AE955207664E6567A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_07EEABED0451EF2C48A4207664E69A57" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_40E8C5517B67EE1AE955207664E6567A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationSettlementAmount" xlink:label="loc_us-gaap_LitigationSettlementAmount_A34E33EDC7C8C298C410207664E67B3B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E4D93115A6B0C18A9899207664E68B59" xlink:to="loc_us-gaap_LitigationSettlementAmount_A34E33EDC7C8C298C410207664E67B3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationSettlementExpense" xlink:label="loc_us-gaap_LitigationSettlementExpense_0DDDFC89B5C238086FA1207664E672A8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_E4D93115A6B0C18A9899207664E68B59" xlink:to="loc_us-gaap_LitigationSettlementExpense_0DDDFC89B5C238086FA1207664E672A8" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveLossUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsBalanceSheetDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CondensedFinancialStatementsCaptionsLineItems" xlink:label="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_96F10EC334DA4D72C2BF2076642315BD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfCondensedFinancialStatementsTable" xlink:label="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F2DAAFDC5288A3232D7E2076642272AD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_96F10EC334DA4D72C2BF2076642315BD" xlink:to="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F2DAAFDC5288A3232D7E2076642272AD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_F1D83045B19BF40BBBE92076642268DC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F2DAAFDC5288A3232D7E2076642272AD" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_F1D83045B19BF40BBBE92076642268DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_C658F017DD97A8A8E96A207664229BE8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_F1D83045B19BF40BBBE92076642268DC" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_C658F017DD97A8A8E96A207664229BE8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_C658F017DD97A8A8E96A207664229BE8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_F1D83045B19BF40BBBE92076642268DC" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_C658F017DD97A8A8E96A207664229BE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_8C8A1B1C2610537D3852207664227921" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_C658F017DD97A8A8E96A207664229BE8" xlink:to="loc_us-gaap_SeniorNotesMember_8C8A1B1C2610537D3852207664227921" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_BB62140640217A4624D120766422C193" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F2DAAFDC5288A3232D7E2076642272AD" xlink:to="loc_us-gaap_DebtInstrumentAxis_BB62140640217A4624D120766422C193" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_C51C0488321E6D9F8AEA20766422EF3E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_BB62140640217A4624D120766422C193" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_C51C0488321E6D9F8AEA20766422EF3E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_C51C0488321E6D9F8AEA20766422EF3E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_BB62140640217A4624D120766422C193" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_C51C0488321E6D9F8AEA20766422EF3E" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_SevenPercentSeniorNotesDue2019Member" xlink:label="loc_ktos_SevenPercentSeniorNotesDue2019Member_93048E3CBEDDB9855C0F20766422D6D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_C51C0488321E6D9F8AEA20766422EF3E" xlink:to="loc_ktos_SevenPercentSeniorNotesDue2019Member_93048E3CBEDDB9855C0F20766422D6D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_2C36964B09C26231C35920766422AE2D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F2DAAFDC5288A3232D7E2076642272AD" xlink:to="loc_dei_LegalEntityAxis_2C36964B09C26231C35920766422AE2D" 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_E8A3C51D427DB239E6A420766422B64E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_2C36964B09C26231C35920766422AE2D" xlink:to="loc_dei_EntityDomain_E8A3C51D427DB239E6A420766422B64E_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_E8A3C51D427DB239E6A420766422B64E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_2C36964B09C26231C35920766422AE2D" xlink:to="loc_dei_EntityDomain_E8A3C51D427DB239E6A420766422B64E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsidiariesMember" xlink:label="loc_us-gaap_SubsidiariesMember_8CCE66815AD979C28E5320766423CB67" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_E8A3C51D427DB239E6A420766422B64E" xlink:to="loc_us-gaap_SubsidiariesMember_8CCE66815AD979C28E5320766423CB67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ParentCompanyMember" xlink:label="loc_us-gaap_ParentCompanyMember_6F247AEB41DB12343F3D207664238C09" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_E8A3C51D427DB239E6A420766422B64E" xlink:to="loc_us-gaap_ParentCompanyMember_6F247AEB41DB12343F3D207664238C09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GuarantorSubsidiariesMember" xlink:label="loc_us-gaap_GuarantorSubsidiariesMember_0EC6D9439B60B39D6F45207664232D15" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_E8A3C51D427DB239E6A420766422B64E" xlink:to="loc_us-gaap_GuarantorSubsidiariesMember_0EC6D9439B60B39D6F45207664232D15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NonGuarantorSubsidiariesMember" xlink:label="loc_us-gaap_NonGuarantorSubsidiariesMember_2E784EBBA19F4E818CC2207664239991" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_E8A3C51D427DB239E6A420766422B64E" xlink:to="loc_us-gaap_NonGuarantorSubsidiariesMember_2E784EBBA19F4E818CC2207664239991" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_881D61ED1291EFAA793D207DB67BC9AC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_F2DAAFDC5288A3232D7E2076642272AD" xlink:to="loc_us-gaap_ConsolidationItemsAxis_881D61ED1291EFAA793D207DB67BC9AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_A51184379CE850D2199F207DB92ED538_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_881D61ED1291EFAA793D207DB67BC9AC" xlink:to="loc_us-gaap_ConsolidationItemsDomain_A51184379CE850D2199F207DB92ED538_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_A51184379CE850D2199F207DB92ED538" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_881D61ED1291EFAA793D207DB67BC9AC" xlink:to="loc_us-gaap_ConsolidationItemsDomain_A51184379CE850D2199F207DB92ED538" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationEliminationsMember" xlink:label="loc_us-gaap_ConsolidationEliminationsMember_FA72A7D522C16950C1BD20766423A0F9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_A51184379CE850D2199F207DB92ED538" xlink:to="loc_us-gaap_ConsolidationEliminationsMember_FA72A7D522C16950C1BD20766423A0F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_94DE46925814BA745FB920766423B71C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_96F10EC334DA4D72C2BF2076642315BD" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_94DE46925814BA745FB920766423B71C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_1F2AF1092D2880F1928020766423D3E4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_96F10EC334DA4D72C2BF2076642315BD" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_1F2AF1092D2880F1928020766423D3E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_96F10EC334DA4D72C2BF2076642315BD" xlink:to="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:to="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_76A3631AF842741A83C820766424D852" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_76A3631AF842741A83C820766424D852" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_96BC9D1EED927A5C91CA207664249A4C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_96BC9D1EED927A5C91CA207664249A4C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DueFromAffiliateCurrent" xlink:label="loc_us-gaap_DueFromAffiliateCurrent_BB34EA6106170E6A777B207664241D5E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:to="loc_us-gaap_DueFromAffiliateCurrent_BB34EA6106170E6A777B207664241D5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings" xlink:label="loc_us-gaap_InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings_907B996DFF90C25E438A207664247EC4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:to="loc_us-gaap_InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings_907B996DFF90C25E438A207664247EC4" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_RestrictedCashAndCashEquivalentsAtCarryingValuePrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_ktos_RestrictedCashAndCashEquivalentsAtCarryingValuePrepaidExpenseAndOtherAssetsCurrent_1B8074547D7028778FE520766424E83A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:to="loc_ktos_RestrictedCashAndCashEquivalentsAtCarryingValuePrepaidExpenseAndOtherAssetsCurrent_1B8074547D7028778FE520766424E83A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_661EDC09DBA104410B7E207664248BEC" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_4D94AB1F6DDC8A63942220766424AB3C" xlink:to="loc_us-gaap_AssetsCurrent_661EDC09DBA104410B7E207664248BEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_061BC298F639374A164520766424C649" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_061BC298F639374A164520766424C649" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_6E9A0FF1DF2E83F012232076642485DD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:to="loc_us-gaap_Goodwill_6E9A0FF1DF2E83F012232076642485DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_ACA26CACE4F0FF5212EF207664246D36" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_ACA26CACE4F0FF5212EF207664246D36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_747BFE063AD82AF6CAD920766424DDD2" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_747BFE063AD82AF6CAD920766424DDD2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_910BE5E9E902865E10C9207664248FBB" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_910BE5E9E902865E10C9207664248FBB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_715B719A4C2ACE4A0BF020766425697E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_1D08BFBB805B8BC49D1F20766424BC31" xlink:to="loc_us-gaap_Assets_715B719A4C2ACE4A0BF020766425697E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_96F10EC334DA4D72C2BF2076642315BD" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_9E880A158AE32E59F2ED20766425D1AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_us-gaap_AccountsPayableCurrent_9E880A158AE32E59F2ED20766425D1AB" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_AccruedExpensesCurrent" xlink:label="loc_ktos_AccruedExpensesCurrent_BC0B9FC0B09FADF8D06E2076642530E1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_ktos_AccruedExpensesCurrent_BC0B9FC0B09FADF8D06E2076642530E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_B7061CF254826EA61BE12076642569BE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_B7061CF254826EA61BE12076642569BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BillingsInExcessOfCost" xlink:label="loc_us-gaap_BillingsInExcessOfCost_2327B8FF171292107F0520766425E53C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_us-gaap_BillingsInExcessOfCost_2327B8FF171292107F0520766425E53C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DueToAffiliateCurrent" xlink:label="loc_us-gaap_DueToAffiliateCurrent_37E964C51D4FA609B03D20766425CE97" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_us-gaap_DueToAffiliateCurrent_37E964C51D4FA609B03D20766425CE97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_30F7FBEA2C5DE6B77149207664253E20" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_30F7FBEA2C5DE6B77149207664253E20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_A74D236C46C355EEA7602076642570FE" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_A74D236C46C355EEA7602076642570FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_F97CDF76679F3D544226207664257C8B" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0A2A18CC93063C2E9376207664252227" xlink:to="loc_us-gaap_LiabilitiesCurrent_F97CDF76679F3D544226207664257C8B" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_LongTermDebtAndUnamortizedPremiumNoncurrent" xlink:label="loc_ktos_LongTermDebtAndUnamortizedPremiumNoncurrent_268ACD2C1E9C3D1AAFFC20766425DCCB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:to="loc_ktos_LongTermDebtAndUnamortizedPremiumNoncurrent_268ACD2C1E9C3D1AAFFC20766425DCCB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_8AB5170A35F03A08498420766425EB83" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_8AB5170A35F03A08498420766425EB83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_23ECCA5873FEE2520C9E207664250A68" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_23ECCA5873FEE2520C9E207664250A68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_AC595F3E1A6AF53D0E1120766425855B" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:to="loc_us-gaap_Liabilities_AC595F3E1A6AF53D0E1120766425855B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_8F230CC35F5B50C5626A20766426FB8D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_8F230CC35F5B50C5626A20766426FB8D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_E95DEDE39CC6CC72C899207664266539" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_9A7C15EAD0D6F9A16D5520766425A782" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_E95DEDE39CC6CC72C899207664266539" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsCondensedConsolidatingFinancialStatementsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsStatementOfCashFlowsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CondensedFinancialStatementsCaptionsLineItems" xlink:label="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfCondensedFinancialStatementsTable" xlink:label="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_5D7FE223B67E39B4C732B09ECA2804BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_5D7FE223B67E39B4C732B09ECA2804BF" 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_327ECAB999D92CDE644BB09ECA28A88F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_5D7FE223B67E39B4C732B09ECA2804BF" xlink:to="loc_dei_LegalEntityAxis_327ECAB999D92CDE644BB09ECA28A88F" 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_342F9585850C2616B346B09ECA29992B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_327ECAB999D92CDE644BB09ECA28A88F" xlink:to="loc_dei_EntityDomain_342F9585850C2616B346B09ECA29992B_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_342F9585850C2616B346B09ECA29992B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_327ECAB999D92CDE644BB09ECA28A88F" xlink:to="loc_dei_EntityDomain_342F9585850C2616B346B09ECA29992B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ParentCompanyMember" xlink:label="loc_us-gaap_ParentCompanyMember_F4ED9918B467F357F5DCB09ECA29067E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_342F9585850C2616B346B09ECA29992B" xlink:to="loc_us-gaap_ParentCompanyMember_F4ED9918B467F357F5DCB09ECA29067E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GuarantorSubsidiariesMember" xlink:label="loc_us-gaap_GuarantorSubsidiariesMember_588BFD8ACFA1C1DDCA55B09ECA29A140" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_342F9585850C2616B346B09ECA29992B" xlink:to="loc_us-gaap_GuarantorSubsidiariesMember_588BFD8ACFA1C1DDCA55B09ECA29A140" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NonGuarantorSubsidiariesMember" xlink:label="loc_us-gaap_NonGuarantorSubsidiariesMember_40AB8BD13C6B7DDB5FEEB09ECA29F355" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_342F9585850C2616B346B09ECA29992B" xlink:to="loc_us-gaap_NonGuarantorSubsidiariesMember_40AB8BD13C6B7DDB5FEEB09ECA29F355" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_C2AA5E5400517C9282DBB09ECA296DC9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_5D7FE223B67E39B4C732B09ECA2804BF" xlink:to="loc_us-gaap_ConsolidationItemsAxis_C2AA5E5400517C9282DBB09ECA296DC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_5408A780AD3954EE64ECB09ECA298A82_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_C2AA5E5400517C9282DBB09ECA296DC9" xlink:to="loc_us-gaap_ConsolidationItemsDomain_5408A780AD3954EE64ECB09ECA298A82_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_5408A780AD3954EE64ECB09ECA298A82" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_C2AA5E5400517C9282DBB09ECA296DC9" xlink:to="loc_us-gaap_ConsolidationItemsDomain_5408A780AD3954EE64ECB09ECA298A82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationEliminationsMember" xlink:label="loc_us-gaap_ConsolidationEliminationsMember_ECFA08B2F4931DA1FB37B09ECA29630E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_5408A780AD3954EE64ECB09ECA298A82" xlink:to="loc_us-gaap_ConsolidationEliminationsMember_ECFA08B2F4931DA1FB37B09ECA29630E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations_62EBA2B1F7BD869A83B8B09ECA2AABF2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations_62EBA2B1F7BD869A83B8B09ECA2AABF2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_9E5938753DF827D3B4DDB09ECA2AE73C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_9E5938753DF827D3B4DDB09ECA2AE73C" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_PaymentsForProceedsFromInvestmentInAffiliatedCompanies" xlink:label="loc_ktos_PaymentsForProceedsFromInvestmentInAffiliatedCompanies_4302679E613E924024D9B09ECA2A1836" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_9E5938753DF827D3B4DDB09ECA2AE73C" xlink:to="loc_ktos_PaymentsForProceedsFromInvestmentInAffiliatedCompanies_4302679E613E924024D9B09ECA2A1836" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsForProceedsFromProductiveAssets" xlink:label="loc_us-gaap_PaymentsForProceedsFromProductiveAssets_D0B3A235606B45BCFF9AB09ECA2A607F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_9E5938753DF827D3B4DDB09ECA2AE73C" xlink:to="loc_us-gaap_PaymentsForProceedsFromProductiveAssets_D0B3A235606B45BCFF9AB09ECA2A607F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_E0C3B98AD0904384C2BCB09ECA2AC170" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_9E5938753DF827D3B4DDB09ECA2AE73C" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_E0C3B98AD0904384C2BCB09ECA2AC170" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_30C3770F3B0BF56A0C25B09ECA2AD474" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_30C3770F3B0BF56A0C25B09ECA2AD474" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_3B7FE44E51C31F593E41B09ECA2AB124" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_3B7FE44E51C31F593E41B09ECA2AB124" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_3D6BC2EB1A58483D0695B09ECA2A81C6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_3D6BC2EB1A58483D0695B09ECA2A81C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromRepurchaseOfEquity" xlink:label="loc_us-gaap_ProceedsFromRepurchaseOfEquity_03640DA6A668A23B2FB5B09ECA2A317D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:to="loc_us-gaap_ProceedsFromRepurchaseOfEquity_03640DA6A668A23B2FB5B09ECA2A317D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromContributionsFromAffiliates" xlink:label="loc_us-gaap_ProceedsFromContributionsFromAffiliates_8F5E652FBB64364B1323B09ECA2BB305" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:to="loc_us-gaap_ProceedsFromContributionsFromAffiliates_8F5E652FBB64364B1323B09ECA2BB305" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_060616E41C6D5D763009B09ECA2B4A94" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_104C71FD43A7F40E337EB09ECA2A6E26" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_060616E41C6D5D763009B09ECA2B4A94" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInContinuingOperations_54EC3B0173F5B0F29CFEB09ECA2B2871" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_NetCashProvidedByUsedInContinuingOperations_54EC3B0173F5B0F29CFEB09ECA2B2871" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" xlink:label="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations_09548C8BC91D8501EF3DB09ECA2BE4FA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations_09548C8BC91D8501EF3DB09ECA2BE4FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" xlink:label="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_8B932E786764CA782F63B09ECA2B60C7" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_8B932E786764CA782F63B09ECA2B60C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_B04B095E87AAE59E7BFDB09ECA2BF4A8" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_F5A2A200B3DB25072430B09ECA294F81" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_B04B095E87AAE59E7BFDB09ECA2BF4A8" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/CondensedConsolidatingFinancialStatementsStatementOfOperationsAndComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CondensedFinancialStatementsCaptionsLineItems" xlink:label="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfCondensedFinancialStatementsTable" xlink:label="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_46FE0F6DAA9493EB6B2FB09ECA367587" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_46FE0F6DAA9493EB6B2FB09ECA367587" 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_801383A0C36091735B33B09ECA36151B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_46FE0F6DAA9493EB6B2FB09ECA367587" xlink:to="loc_dei_LegalEntityAxis_801383A0C36091735B33B09ECA36151B" 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_8A61700D9EED51F7CB6EB09ECA36E12E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_801383A0C36091735B33B09ECA36151B" xlink:to="loc_dei_EntityDomain_8A61700D9EED51F7CB6EB09ECA36E12E_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_8A61700D9EED51F7CB6EB09ECA36E12E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_801383A0C36091735B33B09ECA36151B" xlink:to="loc_dei_EntityDomain_8A61700D9EED51F7CB6EB09ECA36E12E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ParentCompanyMember" xlink:label="loc_us-gaap_ParentCompanyMember_83076D2DFA0A32C34E36B09ECA365B39" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_8A61700D9EED51F7CB6EB09ECA36E12E" xlink:to="loc_us-gaap_ParentCompanyMember_83076D2DFA0A32C34E36B09ECA365B39" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GuarantorSubsidiariesMember" xlink:label="loc_us-gaap_GuarantorSubsidiariesMember_BB1F61BD832D5A237A82B09ECA36A2AD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_8A61700D9EED51F7CB6EB09ECA36E12E" xlink:to="loc_us-gaap_GuarantorSubsidiariesMember_BB1F61BD832D5A237A82B09ECA36A2AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NonGuarantorSubsidiariesMember" xlink:label="loc_us-gaap_NonGuarantorSubsidiariesMember_1D5BB868FC9B05D258B3B09ECA36C346" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_8A61700D9EED51F7CB6EB09ECA36E12E" xlink:to="loc_us-gaap_NonGuarantorSubsidiariesMember_1D5BB868FC9B05D258B3B09ECA36C346" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_EC8E55FAF959D48A432AB09ECA363F01" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCondensedFinancialStatementsTable_46FE0F6DAA9493EB6B2FB09ECA367587" xlink:to="loc_us-gaap_ConsolidationItemsAxis_EC8E55FAF959D48A432AB09ECA363F01" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_1ADD73603D7D7FAA148EB09ECA365CFF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_EC8E55FAF959D48A432AB09ECA363F01" xlink:to="loc_us-gaap_ConsolidationItemsDomain_1ADD73603D7D7FAA148EB09ECA365CFF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_1ADD73603D7D7FAA148EB09ECA365CFF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_EC8E55FAF959D48A432AB09ECA363F01" xlink:to="loc_us-gaap_ConsolidationItemsDomain_1ADD73603D7D7FAA148EB09ECA365CFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationEliminationsMember" xlink:label="loc_us-gaap_ConsolidationEliminationsMember_AA16295A377CC2D0A5D6B09ECA375231" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_1ADD73603D7D7FAA148EB09ECA365CFF" xlink:to="loc_us-gaap_ConsolidationEliminationsMember_AA16295A377CC2D0A5D6B09ECA375231" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueServicesNet" xlink:label="loc_us-gaap_SalesRevenueServicesNet_DE6F238DFC3D5FCCBA97B09ECA37197B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_SalesRevenueServicesNet_DE6F238DFC3D5FCCBA97B09ECA37197B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:label="loc_us-gaap_SalesRevenueGoodsNet_DEF51A0BF5A81C543DDEB09ECA377FDC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_SalesRevenueGoodsNet_DEF51A0BF5A81C543DDEB09ECA377FDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_B5AA0EECC66ECCE409FBB09ECA37245C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_SalesRevenueNet_B5AA0EECC66ECCE409FBB09ECA37245C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostOfServices" xlink:label="loc_us-gaap_CostOfServices_F0ACCD6F2A434519EF94B09ECA373FD6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_CostOfServices_F0ACCD6F2A434519EF94B09ECA373FD6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostOfGoodsSold" xlink:label="loc_us-gaap_CostOfGoodsSold_DB2D2E6BB040EEAF5577B09ECA378EE1" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_CostOfGoodsSold_DB2D2E6BB040EEAF5577B09ECA378EE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_8BA30D1E7A184F020EDFB09ECA379B6C" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_CostOfRevenue_8BA30D1E7A184F020EDFB09ECA379B6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_FF5C5A5C7AE80740AA08B09ECA379750" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_GrossProfit_FF5C5A5C7AE80740AA08B09ECA379750" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_SellingGeneralAndAdministrativeExpenseBusinessAcquisitionRelatedCostsAndOtherImpairmentCharges" xlink:label="loc_ktos_SellingGeneralAndAdministrativeExpenseBusinessAcquisitionRelatedCostsAndOtherImpairmentCharges_27E91F840BF88E99E020B09ECA37BF7E" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_ktos_SellingGeneralAndAdministrativeExpenseBusinessAcquisitionRelatedCostsAndOtherImpairmentCharges_27E91F840BF88E99E020B09ECA37BF7E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_FC558B263DE9B3D6BAE6B09ECA374910" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_FC558B263DE9B3D6BAE6B09ECA374910" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_B019157498171E48BADEB09ECA373C61" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_OperatingIncomeLoss_B019157498171E48BADEB09ECA373C61" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseAbstract" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_16045491E3769DCEE5DAB09ECA38A7C1" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_16045491E3769DCEE5DAB09ECA38A7C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_629B643BA4F729962726B09ECA38C61A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_16045491E3769DCEE5DAB09ECA38A7C1" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_629B643BA4F729962726B09ECA38C61A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_FE80043BFE823A8BB04FB09ECA381C9F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_16045491E3769DCEE5DAB09ECA38A7C1" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_FE80043BFE823A8BB04FB09ECA381C9F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_624B56D52BED7930059DB09ECA38CEFE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_16045491E3769DCEE5DAB09ECA38A7C1" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_624B56D52BED7930059DB09ECA38CEFE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_63BEE0AAA818DF1D8A0DB09ECA387472" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_16045491E3769DCEE5DAB09ECA38A7C1" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_63BEE0AAA818DF1D8A0DB09ECA387472" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_74C08BF92223177ECB8AB09ECA38DA74" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_74C08BF92223177ECB8AB09ECA38DA74" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_7CFA24D46CE4D254B9B7B09ECA380F64" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_7CFA24D46CE4D254B9B7B09ECA380F64" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_D87DC9CEBF9A44BB3871B09ECA387D60" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_D87DC9CEBF9A44BB3871B09ECA387D60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_D13E06670E3B5D463E1DB09ECA3856BE" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_D13E06670E3B5D463E1DB09ECA3856BE" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_EquityInNetIncomeLossOfSubsidiaries" xlink:label="loc_ktos_EquityInNetIncomeLossOfSubsidiaries_AF7FABBE8C49472BAAF5B09ECA38AB74" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_ktos_EquityInNetIncomeLossOfSubsidiaries_AF7FABBE8C49472BAAF5B09ECA38AB74" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_09509C87F1DE445FA7C7B09ECA384C1E" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_NetIncomeLoss_09509C87F1DE445FA7C7B09ECA384C1E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_A9B4E7066CCD510D6119B09ECA38A3C0" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CondensedFinancialStatementsCaptionsLineItems_D49ABA08844A9E5E02D3B09ECA373ED5" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_A9B4E7066CCD510D6119B09ECA38A3C0" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_570BFAFF7049DB58D74582E5D761A564" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:to="loc_us-gaap_CreditFacilityAxis_570BFAFF7049DB58D74582E5D761A564" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_570BFAFF7049DB58D74582E5D761A564" xlink:to="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_570BFAFF7049DB58D74582E5D761A564" xlink:to="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_4EAD07973303DCD0B5CB82E5D761B164" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_4EAD07973303DCD0B5CB82E5D761B164" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember_203833531E70D3DE727E82E5D7616E33" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989" xlink:to="loc_us-gaap_LetterOfCreditMember_203833531E70D3DE727E82E5D7616E33" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_SwingLineLoanMember" xlink:label="loc_ktos_SwingLineLoanMember_CF17903BD4A54560015382E5D761E704" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989" xlink:to="loc_ktos_SwingLineLoanMember_CF17903BD4A54560015382E5D761E704" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_RevolvingLoanSwinglineLoanandLineofCreditMember" xlink:label="loc_ktos_RevolvingLoanSwinglineLoanandLineofCreditMember_58D3669737FE4AFEB9D982E5D761EBAE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_9C955D289AC0ECB1688082E5D761B989" xlink:to="loc_ktos_RevolvingLoanSwinglineLoanandLineofCreditMember_58D3669737FE4AFEB9D982E5D761EBAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_E9AE5796B0A45E77FF6682E5D76196D5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:to="loc_us-gaap_StatementScenarioAxis_E9AE5796B0A45E77FF6682E5D76196D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_BBA5526B06CEF9216C6682E5D761406A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_E9AE5796B0A45E77FF6682E5D76196D5" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_BBA5526B06CEF9216C6682E5D761406A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_BBA5526B06CEF9216C6682E5D761406A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_E9AE5796B0A45E77FF6682E5D76196D5" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_BBA5526B06CEF9216C6682E5D761406A" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_ScenarioOneMember" xlink:label="loc_ktos_ScenarioOneMember_AC8B8DBEEA48B2A7545B82E5D76133CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_BBA5526B06CEF9216C6682E5D761406A" xlink:to="loc_ktos_ScenarioOneMember_AC8B8DBEEA48B2A7545B82E5D76133CB" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_ScenarioTwoMember" xlink:label="loc_ktos_ScenarioTwoMember_55DFE12FE605B53AEC7C82E5D761A228" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_BBA5526B06CEF9216C6682E5D761406A" xlink:to="loc_ktos_ScenarioTwoMember_55DFE12FE605B53AEC7C82E5D761A228" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_ScenarioFiveMember" xlink:label="loc_ktos_ScenarioFiveMember_D3EA5624C79CD27B8D9882E5D761B680" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_BBA5526B06CEF9216C6682E5D761406A" xlink:to="loc_ktos_ScenarioFiveMember_D3EA5624C79CD27B8D9882E5D761B680" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_ScenarioThreeMember" xlink:label="loc_ktos_ScenarioThreeMember_324D3A39C8E80F1F02F982E5D76110B5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ktos_ScenarioFiveMember_D3EA5624C79CD27B8D9882E5D761B680" xlink:to="loc_ktos_ScenarioThreeMember_324D3A39C8E80F1F02F982E5D76110B5" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_ScenarioFourMember" xlink:label="loc_ktos_ScenarioFourMember_4996CCA315882953D2DA82E5D76275D8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ktos_ScenarioFiveMember_D3EA5624C79CD27B8D9882E5D761B680" xlink:to="loc_ktos_ScenarioFourMember_4996CCA315882953D2DA82E5D76275D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_11FD6441F86DAB687B9582E5D762B9E2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:to="loc_us-gaap_DebtInstrumentAxis_11FD6441F86DAB687B9582E5D762B9E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_29F9FDA0CD5167C4D14D82E5D762391F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_11FD6441F86DAB687B9582E5D762B9E2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_29F9FDA0CD5167C4D14D82E5D762391F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_29F9FDA0CD5167C4D14D82E5D762391F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_11FD6441F86DAB687B9582E5D762B9E2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_29F9FDA0CD5167C4D14D82E5D762391F" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_TwoThousandFourteenCreditAgreementThirdAmendmentMember" xlink:label="loc_ktos_TwoThousandFourteenCreditAgreementThirdAmendmentMember_9834A3748BAA8174A16682E5D762B546" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_29F9FDA0CD5167C4D14D82E5D762391F" xlink:to="loc_ktos_TwoThousandFourteenCreditAgreementThirdAmendmentMember_9834A3748BAA8174A16682E5D762B546" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_TwoThousandFourteenCreditAgreementFourthAmendmentMember" xlink:label="loc_ktos_TwoThousandFourteenCreditAgreementFourthAmendmentMember_47F399ACDF76E5CB163382E5D7620A3B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_29F9FDA0CD5167C4D14D82E5D762391F" xlink:to="loc_ktos_TwoThousandFourteenCreditAgreementFourthAmendmentMember_47F399ACDF76E5CB163382E5D7620A3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_E33B527E966BC6AFC73682E5D762D556" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:to="loc_us-gaap_VariableRateAxis_E33B527E966BC6AFC73682E5D762D556" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_E33B527E966BC6AFC73682E5D762D556" xlink:to="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_E33B527E966BC6AFC73682E5D762D556" xlink:to="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FederalFundsEffectiveSwapRateMember" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember_A804137957B151C18C7282E5D762F701" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163" xlink:to="loc_us-gaap_FederalFundsEffectiveSwapRateMember_A804137957B151C18C7282E5D762F701" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_748799354E537E868BAF82E5D762B4AF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_748799354E537E868BAF82E5D762B4AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BaseRateMember" xlink:label="loc_us-gaap_BaseRateMember_7A8F9A40BB4F9494907382E5D762BB89" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163" xlink:to="loc_us-gaap_BaseRateMember_7A8F9A40BB4F9494907382E5D762BB89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EurodollarMember" xlink:label="loc_us-gaap_EurodollarMember_5CD759CB2C726D7B558D82E5D7627390" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_5537EAAE2C2F533A7A4082E5D7623163" xlink:to="loc_us-gaap_EurodollarMember_5CD759CB2C726D7B558D82E5D7627390" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_A7FCF2FC6EF1625D08F982E5D7625645" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:to="loc_us-gaap_RangeAxis_A7FCF2FC6EF1625D08F982E5D7625645" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_CA3366551D5A99A42A0382E5D76275C7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_A7FCF2FC6EF1625D08F982E5D7625645" xlink:to="loc_us-gaap_RangeMember_CA3366551D5A99A42A0382E5D76275C7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_CA3366551D5A99A42A0382E5D76275C7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_A7FCF2FC6EF1625D08F982E5D7625645" xlink:to="loc_us-gaap_RangeMember_CA3366551D5A99A42A0382E5D76275C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_95E0F5DA406FA62AD40A82E5D762AEF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_CA3366551D5A99A42A0382E5D76275C7" xlink:to="loc_us-gaap_MinimumMember_95E0F5DA406FA62AD40A82E5D762AEF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_619CF09300EDB1DE831A82E5D762EB3A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_CA3366551D5A99A42A0382E5D76275C7" xlink:to="loc_us-gaap_MaximumMember_619CF09300EDB1DE831A82E5D762EB3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_76B2305BF6DBD5C8A9F382E5D7629F08" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_E505C98DFE2C91BA44B682E5D761FB9C" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_76B2305BF6DBD5C8A9F382E5D7629F08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_FE67134344EE595AF4BE82E5D762E2A3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_76B2305BF6DBD5C8A9F382E5D7629F08" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_FE67134344EE595AF4BE82E5D762E2A3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_FE67134344EE595AF4BE82E5D762E2A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_76B2305BF6DBD5C8A9F382E5D7629F08" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_FE67134344EE595AF4BE82E5D762E2A3" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_HerleyIndustriesIncMember" xlink:label="loc_ktos_HerleyIndustriesIncMember_90F094BEB4D796E2710682E5D7635CB3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_FE67134344EE595AF4BE82E5D762E2A3" xlink:to="loc_ktos_HerleyIndustriesIncMember_90F094BEB4D796E2710682E5D7635CB3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_3445EC104CE67C3B905882E5D7639869" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_3445EC104CE67C3B905882E5D7639869" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentMaturityPeriod" xlink:label="loc_ktos_DebtInstrumentMaturityPeriod_CA79F1F98AD7A1CC99A482E5D763697A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_DebtInstrumentMaturityPeriod_CA79F1F98AD7A1CC99A482E5D763697A" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_LineOfCreditFacilityMaximumPossibleBorrowingsSubjectToApplicationAndBankApproval" xlink:label="loc_ktos_LineOfCreditFacilityMaximumPossibleBorrowingsSubjectToApplicationAndBankApproval_45A45B411B098FEA35E582E5D7630116" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_LineOfCreditFacilityMaximumPossibleBorrowingsSubjectToApplicationAndBankApproval_45A45B411B098FEA35E582E5D7630116" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentFixedChargeCoverageRatio" xlink:label="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_A4544677A099C459AF3B82E5D763FB66" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_A4544677A099C459AF3B82E5D763FB66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum_3E6E4EBB186A55B53F8282E5D7631A74" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum_3E6E4EBB186A55B53F8282E5D7631A74" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum_22AE9079055D0262E20E82E5D7631C67" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum_22AE9079055D0262E20E82E5D7631C67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_F98A7CAC23AAEBC763A282E5D7636F3C" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_F98A7CAC23AAEBC763A282E5D7636F3C" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_LineofCreditFacilityCovenantComplianceRequiredAmountofLoanRepurchased" xlink:label="loc_ktos_LineofCreditFacilityCovenantComplianceRequiredAmountofLoanRepurchased_AC8B39AC38077D4E5F7E82E5D76321F0" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_LineofCreditFacilityCovenantComplianceRequiredAmountofLoanRepurchased_AC8B39AC38077D4E5F7E82E5D76321F0" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_LineofCreditFacilityCovenantTermsCapacityofOutstandingBorrowing" xlink:label="loc_ktos_LineofCreditFacilityCovenantTermsCapacityofOutstandingBorrowing_AB4EF52C4492282722DC82E5D763201B" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_LineofCreditFacilityCovenantTermsCapacityofOutstandingBorrowing_AB4EF52C4492282722DC82E5D763201B" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_LineofCreditFacilityCovenantTermsPercentageofReinvestmentReserveoverOutstandingBorrowingsinExcessofCapacityofOutstandingBorrowing" xlink:label="loc_ktos_LineofCreditFacilityCovenantTermsPercentageofReinvestmentReserveoverOutstandingBorrowingsinExcessofCapacityofOutstandingBorrowing_F6D95F034B710BD7862B82E5D7634859" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_LineofCreditFacilityCovenantTermsPercentageofReinvestmentReserveoverOutstandingBorrowingsinExcessofCapacityofOutstandingBorrowing_F6D95F034B710BD7862B82E5D7634859" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_LineofCreditFacilityCollateralReserveAmount" xlink:label="loc_ktos_LineofCreditFacilityCollateralReserveAmount_B8E7CC36D6EC3263545F82E5D763A87A" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_LineofCreditFacilityCollateralReserveAmount_B8E7CC36D6EC3263545F82E5D763A87A" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentDurationforCollateralAdjustment" xlink:label="loc_ktos_DebtInstrumentDurationforCollateralAdjustment_42237F79713BB0C4062382E5D7631D18" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_DebtInstrumentDurationforCollateralAdjustment_42237F79713BB0C4062382E5D7631D18" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentCollateralAmountIncreaseDecrease" xlink:label="loc_ktos_DebtInstrumentCollateralAmountIncreaseDecrease_D0CE1B98AEEC996E88A882E5D7638CB2" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_DebtInstrumentCollateralAmountIncreaseDecrease_D0CE1B98AEEC996E88A882E5D7638CB2" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentCovenantComplianceCreditLineOutstandingExcludedFromCalculationofMinimumFixedChargeCoverageRatioAmount" xlink:label="loc_ktos_DebtInstrumentCovenantComplianceCreditLineOutstandingExcludedFromCalculationofMinimumFixedChargeCoverageRatioAmount_F8AEB52ACADB84950EE782E5D7639FC0" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_ktos_DebtInstrumentCovenantComplianceCreditLineOutstandingExcludedFromCalculationofMinimumFixedChargeCoverageRatioAmount_F8AEB52ACADB84950EE782E5D7639FC0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_E8A834F3D2EEEC0C25F282E5D7639431" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_us-gaap_LineOfCredit_E8A834F3D2EEEC0C25F282E5D7639431" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_4B49612C1077BA80BC3282E5D763B3A6" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_6CD99120ADE65DCFA44A82E5D7637411" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_4B49612C1077BA80BC3282E5D763B3A6" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_1F94DA08027E5D45A7A2B4F87A216107" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:to="loc_us-gaap_DebtInstrumentTable_1F94DA08027E5D45A7A2B4F87A216107" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_8C43D22611BA5F38B45E7E74236B0741" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1F94DA08027E5D45A7A2B4F87A216107" xlink:to="loc_us-gaap_VariableRateAxis_8C43D22611BA5F38B45E7E74236B0741" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_57DD86ECD4CF327BB3ED34E39CB966B2_6750AE7A543E578E822316B41CB2257C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_8C43D22611BA5F38B45E7E74236B0741" xlink:to="loc_us-gaap_VariableRateDomain_57DD86ECD4CF327BB3ED34E39CB966B2_6750AE7A543E578E822316B41CB2257C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_C301545712855D28BF468B547A390896" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_8C43D22611BA5F38B45E7E74236B0741" xlink:to="loc_us-gaap_VariableRateDomain_C301545712855D28BF468B547A390896" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_25DCAA54CD8956A4ACC0D2036CB76E46" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_C301545712855D28BF468B547A390896" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_25DCAA54CD8956A4ACC0D2036CB76E46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_4C1EED58F0D35FA49C47A6DECCD37DE7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1F94DA08027E5D45A7A2B4F87A216107" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_4C1EED58F0D35FA49C47A6DECCD37DE7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_2AE55E0FA81E7E0D89C834E39CB90030_6750AE7A543E578E822316B41CB2257C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4C1EED58F0D35FA49C47A6DECCD37DE7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_2AE55E0FA81E7E0D89C834E39CB90030_6750AE7A543E578E822316B41CB2257C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5D5732B7E29058A187A3FCCF66FDB284" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4C1EED58F0D35FA49C47A6DECCD37DE7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5D5732B7E29058A187A3FCCF66FDB284" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LoansPayableMember" xlink:label="loc_us-gaap_LoansPayableMember_75FDB159C0AA5BA08A62A01D53484ECE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5D5732B7E29058A187A3FCCF66FDB284" xlink:to="loc_us-gaap_LoansPayableMember_75FDB159C0AA5BA08A62A01D53484ECE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_7AC71A0F59185899AB5B323F146CD832" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_7AC71A0F59185899AB5B323F146CD832" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentMaturityPeriod" xlink:label="loc_ktos_DebtInstrumentMaturityPeriod_0A3580762D9851F6858F4276CC49A8DF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:to="loc_ktos_DebtInstrumentMaturityPeriod_0A3580762D9851F6858F4276CC49A8DF" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_NumberofSubsidiaryOwned" xlink:label="loc_ktos_NumberofSubsidiaryOwned_31DF4D65121D5415BBDF4FF2909EDA72" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:to="loc_ktos_NumberofSubsidiaryOwned_31DF4D65121D5415BBDF4FF2909EDA72" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_82F27F4D1D3A5AB6B921C7D5347502CC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:to="loc_us-gaap_LongTermDebt_82F27F4D1D3A5AB6B921C7D5347502CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_E2BA9B320FE4520D9CFDEB6F0E246086" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_E2BA9B320FE4520D9CFDEB6F0E246086" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_E63D32DAF59353D8B2C78546E7D8059A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_96D81572603E5020B679906332A91A37" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_E63D32DAF59353D8B2C78546E7D8059A" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_B92827ED1A3CBA776DA6CB5AD2232486" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_DebtInstrumentTable_B92827ED1A3CBA776DA6CB5AD2232486" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_BFE25ED75B83B89635DDCB5AD2235F8F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_B92827ED1A3CBA776DA6CB5AD2232486" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_BFE25ED75B83B89635DDCB5AD2235F8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3B379419EA85FF042610CB5AD2232D80_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_BFE25ED75B83B89635DDCB5AD2235F8F" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3B379419EA85FF042610CB5AD2232D80_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_3B379419EA85FF042610CB5AD2232D80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_BFE25ED75B83B89635DDCB5AD2235F8F" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_3B379419EA85FF042610CB5AD2232D80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_94A7E6C31F634646F633CB5AD223F1E6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_3B379419EA85FF042610CB5AD2232D80" xlink:to="loc_us-gaap_SeniorNotesMember_94A7E6C31F634646F633CB5AD223F1E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_68BD522DD9F034067C74CB5AD2237F8D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_B92827ED1A3CBA776DA6CB5AD2232486" xlink:to="loc_us-gaap_DebtInstrumentAxis_68BD522DD9F034067C74CB5AD2237F8D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_D7683F4FE14C10DD1349CB5AD22431B5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_68BD522DD9F034067C74CB5AD2237F8D" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_D7683F4FE14C10DD1349CB5AD22431B5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_D7683F4FE14C10DD1349CB5AD22431B5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_68BD522DD9F034067C74CB5AD2237F8D" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_D7683F4FE14C10DD1349CB5AD22431B5" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_SevenPercentSeniorNotesDue2019Member" xlink:label="loc_ktos_SevenPercentSeniorNotesDue2019Member_CF253D4700C7E8E88935CB5AD2241EDD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_D7683F4FE14C10DD1349CB5AD22431B5" xlink:to="loc_ktos_SevenPercentSeniorNotesDue2019Member_CF253D4700C7E8E88935CB5AD2241EDD" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_TenPercentSeniorNotesDueJune2017Member" xlink:label="loc_ktos_TenPercentSeniorNotesDueJune2017Member_CFEB61E912B1C7B3DE06CB5AD2249D32" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_D7683F4FE14C10DD1349CB5AD22431B5" xlink:to="loc_ktos_TenPercentSeniorNotesDueJune2017Member_CFEB61E912B1C7B3DE06CB5AD2249D32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_2101AAE7CEDA72A6C9E7CB5AD224E517" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_B92827ED1A3CBA776DA6CB5AD2232486" xlink:to="loc_us-gaap_CreditFacilityAxis_2101AAE7CEDA72A6C9E7CB5AD224E517" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_4BE7CC95A9E8225ECEFECB5AD224EDA9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_2101AAE7CEDA72A6C9E7CB5AD224E517" xlink:to="loc_us-gaap_CreditFacilityDomain_4BE7CC95A9E8225ECEFECB5AD224EDA9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_4BE7CC95A9E8225ECEFECB5AD224EDA9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_2101AAE7CEDA72A6C9E7CB5AD224E517" xlink:to="loc_us-gaap_CreditFacilityDomain_4BE7CC95A9E8225ECEFECB5AD224EDA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_DC290202220F6FA0A2C4CB5AD224DC8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4BE7CC95A9E8225ECEFECB5AD224EDA9" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_DC290202220F6FA0A2C4CB5AD224DC8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_E14539EFB7DAD606AA63CB5AD224CA9B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_B92827ED1A3CBA776DA6CB5AD2232486" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_E14539EFB7DAD606AA63CB5AD224CA9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_4BD851A836300F65E7C6CB5AD22425AE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_E14539EFB7DAD606AA63CB5AD224CA9B" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_4BD851A836300F65E7C6CB5AD22425AE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_4BD851A836300F65E7C6CB5AD22425AE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_E14539EFB7DAD606AA63CB5AD224CA9B" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_4BD851A836300F65E7C6CB5AD22425AE" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_RedemptionPeriodTwoMember" xlink:label="loc_ktos_RedemptionPeriodTwoMember_0489FC83E71E1700FC8FCB5AD224470C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_4BD851A836300F65E7C6CB5AD22425AE" xlink:to="loc_ktos_RedemptionPeriodTwoMember_0489FC83E71E1700FC8FCB5AD224470C" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_RedemptionPeriodThreeMember" xlink:label="loc_ktos_RedemptionPeriodThreeMember_54746200331BF3D754B0CB5AD224808E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_4BD851A836300F65E7C6CB5AD22425AE" xlink:to="loc_ktos_RedemptionPeriodThreeMember_54746200331BF3D754B0CB5AD224808E" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_RedemptionPeriodFourMember" xlink:label="loc_ktos_RedemptionPeriodFourMember_9DCC373FA40453EDD567CB5AD224B461" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_4BD851A836300F65E7C6CB5AD22425AE" xlink:to="loc_ktos_RedemptionPeriodFourMember_9DCC373FA40453EDD567CB5AD224B461" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_28744FDAB3176525ABD4CB5AD224B1FE" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_B92827ED1A3CBA776DA6CB5AD2232486" xlink:to="loc_us-gaap_RangeAxis_28744FDAB3176525ABD4CB5AD224B1FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_9128DC99000C79DA6A0ECB5AD2253C39_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_28744FDAB3176525ABD4CB5AD224B1FE" xlink:to="loc_us-gaap_RangeMember_9128DC99000C79DA6A0ECB5AD2253C39_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_9128DC99000C79DA6A0ECB5AD2253C39" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_28744FDAB3176525ABD4CB5AD224B1FE" xlink:to="loc_us-gaap_RangeMember_9128DC99000C79DA6A0ECB5AD2253C39" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_E5C9F82E38518D242E10CB5AD22555F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_9128DC99000C79DA6A0ECB5AD2253C39" xlink:to="loc_us-gaap_MinimumMember_E5C9F82E38518D242E10CB5AD22555F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_AF9595043180AE285B1CCB5AD225AAB7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_9128DC99000C79DA6A0ECB5AD2253C39" xlink:to="loc_us-gaap_MaximumMember_AF9595043180AE285B1CCB5AD225AAB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_5A353EDAD4922AD44D48CB5AD225D216" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_5A353EDAD4922AD44D48CB5AD225D216" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_0C3C0119951E39F794E6CB5AD225E1FB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_0C3C0119951E39F794E6CB5AD225E1FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_38183FBAFA39F70DFB6BCB5AD225DA50" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_38183FBAFA39F70DFB6BCB5AD225DA50" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_6B8C6CBC7555505D816FCB5AD22549F0" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_6B8C6CBC7555505D816FCB5AD22549F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtIssuanceCosts" xlink:label="loc_us-gaap_DebtIssuanceCosts_18831AC0CC3F4A84065CCB5AD2257736" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_DebtIssuanceCosts_18831AC0CC3F4A84065CCB5AD2257736" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_F3F4B6C5058ABDA591E9CB5AD225B838" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_F3F4B6C5058ABDA591E9CB5AD225B838" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentRepurchaseAmount" xlink:label="loc_us-gaap_DebtInstrumentRepurchaseAmount_325110031204DCB7F20ECB5AD225DDE8" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_DebtInstrumentRepurchaseAmount_325110031204DCB7F20ECB5AD225DDE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepaymentsOfDebt" xlink:label="loc_us-gaap_RepaymentsOfDebt_2B3811B8860CCF858067CB5AD22527CB" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_RepaymentsOfDebt_2B3811B8860CCF858067CB5AD22527CB" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentEarlyTerminationFee" xlink:label="loc_ktos_DebtInstrumentEarlyTerminationFee_8BBE098592231B2885A1CB5AD22599E4" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_ktos_DebtInstrumentEarlyTerminationFee_8BBE098592231B2885A1CB5AD22599E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_129DE54B3632D52E4840CB5AD225E545" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_129DE54B3632D52E4840CB5AD225E545" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentUnamortizedPremium" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedPremium_5424C17896E28C1047E7CB5AD225516F" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedPremium_5424C17896E28C1047E7CB5AD225516F" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentEscrowInterestAccrued" xlink:label="loc_ktos_DebtInstrumentEscrowInterestAccrued_B039A8875536806C14DBCB5AD2259767" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_ktos_DebtInstrumentEscrowInterestAccrued_B039A8875536806C14DBCB5AD2259767" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_21C80B7F7F631DF39578CB5AD225B24E" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_21C80B7F7F631DF39578CB5AD225B24E" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentFixedChargeCoverageRatio" xlink:label="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_8A37B5C733D4EA2C359ECB5AD2257034" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_ktos_DebtInstrumentFixedChargeCoverageRatio_8A37B5C733D4EA2C359ECB5AD2257034" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentRedemptionAmountAsPercentageOfAggregatePrincipalAmount" xlink:label="loc_ktos_DebtInstrumentRedemptionAmountAsPercentageOfAggregatePrincipalAmount_4D4A8AA4915B41C7D95ECB5AD225FEAA" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_ktos_DebtInstrumentRedemptionAmountAsPercentageOfAggregatePrincipalAmount_4D4A8AA4915B41C7D95ECB5AD225FEAA" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_DebtInstrumentDurationFollowingSaleRequiredtoRepurchaseLoanWithUnusedProceeds" xlink:label="loc_ktos_DebtInstrumentDurationFollowingSaleRequiredtoRepurchaseLoanWithUnusedProceeds_8DFCF07A4C43D366844ACB5AD22502F2" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_ktos_DebtInstrumentDurationFollowingSaleRequiredtoRepurchaseLoanWithUnusedProceeds_8DFCF07A4C43D366844ACB5AD22502F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_D1B4095291EA1F3AE9A5CB5AD225B652" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_LineOfCredit_D1B4095291EA1F3AE9A5CB5AD225B652" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LegalFees" xlink:label="loc_us-gaap_LegalFees_409B0C76615543B5F19BCB5AD226B97A" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_LegalFees_409B0C76615543B5F19BCB5AD226B97A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_18E165D26ABA6610018CCB5AD2261439" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_18E165D26ABA6610018CCB5AD2261439" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost_8AF38B5826140B0C7ED5CB5AD2260C51" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost_8AF38B5826140B0C7ED5CB5AD2260C51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UnamortizedDebtIssuanceExpense" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_AA6BF32A7C2DD98CE270CB5AD226C37D" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_AA6BF32A7C2DD98CE270CB5AD226C37D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeniorNotes" xlink:label="loc_us-gaap_SeniorNotes_B3A4879EB4F2E17E6F6ACB5AD2263BCD" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_27E251977955025F6072CB5AD22531F3" xlink:to="loc_us-gaap_SeniorNotes_B3A4879EB4F2E17E6F6ACB5AD2263BCD" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_508ACE3A28FBEF1DF2FCB066D5D278F9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_010218B17F909C1E449EB066D5D2A004" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_508ACE3A28FBEF1DF2FCB066D5D278F9" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_010218B17F909C1E449EB066D5D2A004" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_BA435E7E30018FB4133FB066D5D263CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_010218B17F909C1E449EB066D5D2A004" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_BA435E7E30018FB4133FB066D5D263CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_ED6C601A412D755C0A89B066D5D268A9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_BA435E7E30018FB4133FB066D5D263CC" xlink:to="loc_us-gaap_SegmentDomain_ED6C601A412D755C0A89B066D5D268A9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_ED6C601A412D755C0A89B066D5D268A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_BA435E7E30018FB4133FB066D5D263CC" xlink:to="loc_us-gaap_SegmentDomain_ED6C601A412D755C0A89B066D5D268A9" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_KratosGovernmentSolutionsMember" xlink:label="loc_ktos_KratosGovernmentSolutionsMember_8B8720AE102EEE6C2433B066D5D2733D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ED6C601A412D755C0A89B066D5D268A9" xlink:to="loc_ktos_KratosGovernmentSolutionsMember_8B8720AE102EEE6C2433B066D5D2733D" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_C21D021DEE5C9D8A2217B066D5D299ED" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ED6C601A412D755C0A89B066D5D268A9" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_C21D021DEE5C9D8A2217B066D5D299ED" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_KratosUnmannedSystemsMember" xlink:label="loc_ktos_KratosUnmannedSystemsMember_7622AA8F3E5E22988C1AB066D5D2EB64" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_ED6C601A412D755C0A89B066D5D268A9" xlink:to="loc_ktos_KratosUnmannedSystemsMember_7622AA8F3E5E22988C1AB066D5D2EB64" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillGross" xlink:label="loc_us-gaap_GoodwillGross_0532D33C261A2DF50190B066D5D270DC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_508ACE3A28FBEF1DF2FCB066D5D278F9" xlink:to="loc_us-gaap_GoodwillGross_0532D33C261A2DF50190B066D5D270DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_89032408C08CD665BF90B066D5D27C67" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_508ACE3A28FBEF1DF2FCB066D5D278F9" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_89032408C08CD665BF90B066D5D27C67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_4F980F6FCEE15EBDE192B066D5D293CE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_508ACE3A28FBEF1DF2FCB066D5D278F9" xlink:to="loc_us-gaap_Goodwill_4F980F6FCEE15EBDE192B066D5D293CE" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0CF69A794299AD9B73E53ACD9232398D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_16DD149C3C43B0B3D2373ACD92315EB3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0CF69A794299AD9B73E53ACD9232398D" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_16DD149C3C43B0B3D2373ACD92315EB3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1D7B75CA9C2EA57E8C0A3ACD92317FC4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_16DD149C3C43B0B3D2373ACD92315EB3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1D7B75CA9C2EA57E8C0A3ACD92317FC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1D7B75CA9C2EA57E8C0A3ACD92317FC4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1D7B75CA9C2EA57E8C0A3ACD92317FC4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_9C706A95ADB22016C8ED3ACD923261F7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF" xlink:to="loc_us-gaap_CustomerRelationshipsMember_9C706A95ADB22016C8ED3ACD923261F7" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_ContractsAndBacklogMember" xlink:label="loc_ktos_ContractsAndBacklogMember_D9ACACB3C5ED4FF5763C3ACD9232616A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF" xlink:to="loc_ktos_ContractsAndBacklogMember_D9ACACB3C5ED4FF5763C3ACD9232616A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_110BBFF6D4DBC9F74AB43ACD9232960E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_110BBFF6D4DBC9F74AB43ACD9232960E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_96D89F9126ADDD66FCD13ACD92323457" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977CF1CFC4FD96D32363ACD9232D6EF" xlink:to="loc_us-gaap_TradeNamesMember_96D89F9126ADDD66FCD13ACD92323457" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_DF63B9DBC77E9CFEE9E73ACD92322AAC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_16DD149C3C43B0B3D2373ACD92315EB3" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_DF63B9DBC77E9CFEE9E73ACD92322AAC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A6DE09F0F3C485890CA83ACD9232DFA4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_DF63B9DBC77E9CFEE9E73ACD92322AAC" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A6DE09F0F3C485890CA83ACD9232DFA4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A6DE09F0F3C485890CA83ACD9232DFA4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_DF63B9DBC77E9CFEE9E73ACD92322AAC" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A6DE09F0F3C485890CA83ACD9232DFA4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_9EE5261DD72A71218FBF3ACD9232F6B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_A6DE09F0F3C485890CA83ACD9232DFA4" xlink:to="loc_us-gaap_TradeNamesMember_9EE5261DD72A71218FBF3ACD9232F6B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_E6E3FEFE62C92C9D7C733ACD9232EDC3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0CF69A794299AD9B73E53ACD9232398D" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_E6E3FEFE62C92C9D7C733ACD9232EDC3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_3484851BD2D81C429C7B3ACD9232A906" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_E6E3FEFE62C92C9D7C733ACD9232EDC3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_3484851BD2D81C429C7B3ACD9232A906" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_071326BA76C1373CDA613ACD9233FCDF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_E6E3FEFE62C92C9D7C733ACD9232EDC3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_071326BA76C1373CDA613ACD9233FCDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_5EC6B90B3687E96F0E223ACD92335532" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_E6E3FEFE62C92C9D7C733ACD9232EDC3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_5EC6B90B3687E96F0E223ACD92335532" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_E5C299EFE5AF68AC29373ACD92338EF8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0CF69A794299AD9B73E53ACD9232398D" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_E5C299EFE5AF68AC29373ACD92338EF8" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_IntangibleAssetsExcludingGoodwillGross" xlink:label="loc_ktos_IntangibleAssetsExcludingGoodwillGross_400B451F76FDE3505DA03ACD92336183" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0CF69A794299AD9B73E53ACD9232398D" xlink:to="loc_ktos_IntangibleAssetsExcludingGoodwillGross_400B451F76FDE3505DA03ACD92336183" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_42F85AF10C67357DC1AA3ACD92330199" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0CF69A794299AD9B73E53ACD9232398D" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_42F85AF10C67357DC1AA3ACD92330199" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_7C6A3D9F2A5ABF67A5F53ACD92336E83" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_0CF69A794299AD9B73E53ACD9232398D" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_7C6A3D9F2A5ABF67A5F53ACD92336E83" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_FF1480DBA24851ED9BF03B06CB30426A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_71E2F8C01F2E5CE69615EE5ED1374026" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_FF1480DBA24851ED9BF03B06CB30426A" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_71E2F8C01F2E5CE69615EE5ED1374026" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6376C1455AFB5B41AA7BAD02ACF47147" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_71E2F8C01F2E5CE69615EE5ED1374026" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6376C1455AFB5B41AA7BAD02ACF47147" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0684E5D555F500A1B4A27411A2929E36_6750AE7A543E578E822316B41CB2257C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6376C1455AFB5B41AA7BAD02ACF47147" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_0684E5D555F500A1B4A27411A2929E36_6750AE7A543E578E822316B41CB2257C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_73A7C85CF7DC56B18657EC6755DDA0E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_6376C1455AFB5B41AA7BAD02ACF47147" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_73A7C85CF7DC56B18657EC6755DDA0E8" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_StockOptionsAndStockAwardsMember" xlink:label="loc_ktos_StockOptionsAndStockAwardsMember_4A86771D03695FD1B5BF7CE468A8A20C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_73A7C85CF7DC56B18657EC6755DDA0E8" xlink:to="loc_ktos_StockOptionsAndStockAwardsMember_4A86771D03695FD1B5BF7CE468A8A20C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_B8299687FBF856C59BF1998569C6FEEB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_FF1480DBA24851ED9BF03B06CB30426A" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_B8299687FBF856C59BF1998569C6FEEB" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_1F88AB19ACA287A5983ECA5DAF6EED96" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E733BFC9ABC66C1E1A8BCA5DAF6E7E1C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_1F88AB19ACA287A5983ECA5DAF6EED96" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E733BFC9ABC66C1E1A8BCA5DAF6E7E1C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_B9718E5BD11C993DFE70CA5DAF6EC604" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E733BFC9ABC66C1E1A8BCA5DAF6E7E1C" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_B9718E5BD11C993DFE70CA5DAF6EC604" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3212DDFB2F92B2BD6E8DCA5DAF6E78A3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B9718E5BD11C993DFE70CA5DAF6EC604" xlink:to="loc_us-gaap_SegmentDomain_3212DDFB2F92B2BD6E8DCA5DAF6E78A3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3212DDFB2F92B2BD6E8DCA5DAF6E78A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B9718E5BD11C993DFE70CA5DAF6EC604" xlink:to="loc_us-gaap_SegmentDomain_3212DDFB2F92B2BD6E8DCA5DAF6E78A3" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_B49AFA0D4D5884C39BE9CA5DAF6EF7D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3212DDFB2F92B2BD6E8DCA5DAF6E78A3" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_B49AFA0D4D5884C39BE9CA5DAF6EF7D6" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_KratosGovernmentSolutionsMember" xlink:label="loc_ktos_KratosGovernmentSolutionsMember_849E9C1CE03D31A72887CA5DAF6EDFFB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3212DDFB2F92B2BD6E8DCA5DAF6E78A3" xlink:to="loc_ktos_KratosGovernmentSolutionsMember_849E9C1CE03D31A72887CA5DAF6EDFFB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_FAE1E51B9853AB9E6B3CCA5DAF6ECC49" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E733BFC9ABC66C1E1A8BCA5DAF6E7E1C" xlink:to="loc_us-gaap_LitigationStatusAxis_FAE1E51B9853AB9E6B3CCA5DAF6ECC49" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_352250D3EDEDBA2ADCBECA5DAF6EDEFD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_FAE1E51B9853AB9E6B3CCA5DAF6ECC49" xlink:to="loc_us-gaap_LitigationStatusDomain_352250D3EDEDBA2ADCBECA5DAF6EDEFD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_352250D3EDEDBA2ADCBECA5DAF6EDEFD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_FAE1E51B9853AB9E6B3CCA5DAF6ECC49" xlink:to="loc_us-gaap_LitigationStatusDomain_352250D3EDEDBA2ADCBECA5DAF6EDEFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SettledLitigationMember" xlink:label="loc_us-gaap_SettledLitigationMember_B289FF39D9F40FFCE405CA5DAF6E98B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_352250D3EDEDBA2ADCBECA5DAF6EDEFD" xlink:to="loc_us-gaap_SettledLitigationMember_B289FF39D9F40FFCE405CA5DAF6E98B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PublicUtilitiesInventoryAxis" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_4521EB0350293F49077ECA5DAF6EF581" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E733BFC9ABC66C1E1A8BCA5DAF6E7E1C" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_4521EB0350293F49077ECA5DAF6EF581" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_BEE03F4719AA8A9AF431CA5DAF6EF909_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_4521EB0350293F49077ECA5DAF6EF581" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_BEE03F4719AA8A9AF431CA5DAF6EF909_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_BEE03F4719AA8A9AF431CA5DAF6EF909" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_4521EB0350293F49077ECA5DAF6EF581" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_BEE03F4719AA8A9AF431CA5DAF6EF909" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InventoriesMember" xlink:label="loc_us-gaap_InventoriesMember_4E8C9010569E6A13B94ECA5DAF6EAE72" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_BEE03F4719AA8A9AF431CA5DAF6EF909" xlink:to="loc_us-gaap_InventoriesMember_4E8C9010569E6A13B94ECA5DAF6EAE72" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_FB701DE0D72673EBE94CCA5DAF6E6464" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_1F88AB19ACA287A5983ECA5DAF6EED96" xlink:to="loc_us-gaap_NumberOfReportableSegments_FB701DE0D72673EBE94CCA5DAF6E6464" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationSettlementExpense" xlink:label="loc_us-gaap_LitigationSettlementExpense_34F045E017F81EC32E4BCA5DAF6E7041" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_1F88AB19ACA287A5983ECA5DAF6EED96" xlink:to="loc_us-gaap_LitigationSettlementExpense_34F045E017F81EC32E4BCA5DAF6E7041" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaap_AssetImpairmentCharges_6A58175B6D6E0E768F27CA5DAF6E3A2E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_1F88AB19ACA287A5983ECA5DAF6EED96" xlink:to="loc_us-gaap_AssetImpairmentCharges_6A58175B6D6E0E768F27CA5DAF6E3A2E" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_38D37C1E8D2E9D48511DB72F0CF95E59" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_947400DBA9FF824970BAB72F0CF9BE32" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_38D37C1E8D2E9D48511DB72F0CF95E59" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_947400DBA9FF824970BAB72F0CF9BE32" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_93032E6A735C8E278852B72F0CF9870E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_947400DBA9FF824970BAB72F0CF9BE32" xlink:to="loc_us-gaap_ConsolidationItemsAxis_93032E6A735C8E278852B72F0CF9870E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_E3F68BF4698CB1FFB759B72F0CF98835_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_93032E6A735C8E278852B72F0CF9870E" xlink:to="loc_us-gaap_ConsolidationItemsDomain_E3F68BF4698CB1FFB759B72F0CF98835_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_E3F68BF4698CB1FFB759B72F0CF98835" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_93032E6A735C8E278852B72F0CF9870E" xlink:to="loc_us-gaap_ConsolidationItemsDomain_E3F68BF4698CB1FFB759B72F0CF98835" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_B080C6B21E1627D79A09B72F0CF9239A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_E3F68BF4698CB1FFB759B72F0CF98835" xlink:to="loc_us-gaap_OperatingSegmentsMember_B080C6B21E1627D79A09B72F0CF9239A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_DAF8EE1AA48EA19B0CA6B72F0CF97903" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_E3F68BF4698CB1FFB759B72F0CF98835" xlink:to="loc_us-gaap_CorporateNonSegmentMember_DAF8EE1AA48EA19B0CA6B72F0CF97903" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_A6612CC54102CC7FF186B72F0CF91469" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_947400DBA9FF824970BAB72F0CF9BE32" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_A6612CC54102CC7FF186B72F0CF91469" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_4A04DFBBA878FB6ED05CB72F0CF9E00C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_A6612CC54102CC7FF186B72F0CF91469" xlink:to="loc_us-gaap_SegmentDomain_4A04DFBBA878FB6ED05CB72F0CF9E00C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_4A04DFBBA878FB6ED05CB72F0CF9E00C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_A6612CC54102CC7FF186B72F0CF91469" xlink:to="loc_us-gaap_SegmentDomain_4A04DFBBA878FB6ED05CB72F0CF9E00C" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_KratosGovernmentSolutionsMember" xlink:label="loc_ktos_KratosGovernmentSolutionsMember_332DB153FD32D876E3D1B72F0CF9C532" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4A04DFBBA878FB6ED05CB72F0CF9E00C" xlink:to="loc_ktos_KratosGovernmentSolutionsMember_332DB153FD32D876E3D1B72F0CF9C532" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_PublicSafetyAndSecurityMember" xlink:label="loc_ktos_PublicSafetyAndSecurityMember_DCEDA63001488BC7C902B72F0CF9BDE4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4A04DFBBA878FB6ED05CB72F0CF9E00C" xlink:to="loc_ktos_PublicSafetyAndSecurityMember_DCEDA63001488BC7C902B72F0CF9BDE4" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_KratosUnmannedSystemsMember" xlink:label="loc_ktos_KratosUnmannedSystemsMember_AFBD81CF0E56932F411BB72F0CF9157B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4A04DFBBA878FB6ED05CB72F0CF9E00C" xlink:to="loc_ktos_KratosUnmannedSystemsMember_AFBD81CF0E56932F411BB72F0CF9157B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_D4D561806DD63B0D2166B72F0CF99DC7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_38D37C1E8D2E9D48511DB72F0CF95E59" xlink:to="loc_us-gaap_RevenuesAbstract_D4D561806DD63B0D2166B72F0CF99DC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueServicesNet" xlink:label="loc_us-gaap_SalesRevenueServicesNet_4B7CD62FFFD05FABBADFB72F0CF9E841" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_D4D561806DD63B0D2166B72F0CF99DC7" xlink:to="loc_us-gaap_SalesRevenueServicesNet_4B7CD62FFFD05FABBADFB72F0CF9E841" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:label="loc_us-gaap_SalesRevenueGoodsNet_618472EC47FC5529256BB72F0CFA924E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_D4D561806DD63B0D2166B72F0CF99DC7" xlink:to="loc_us-gaap_SalesRevenueGoodsNet_618472EC47FC5529256BB72F0CFA924E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_BBE384AA04F622B3804AB72F0CFA6046" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_D4D561806DD63B0D2166B72F0CF99DC7" xlink:to="loc_us-gaap_SalesRevenueNet_BBE384AA04F622B3804AB72F0CFA6046" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract_9B4D113EDD0D524CA451B72F0CFA7F35" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_38D37C1E8D2E9D48511DB72F0CF95E59" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract_9B4D113EDD0D524CA451B72F0CFA7F35" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_CA0670FDC0B5179548C2B72F0CFA03BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DepreciationDepletionAndAmortizationNonproductionAbstract_9B4D113EDD0D524CA451B72F0CFA7F35" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_CA0670FDC0B5179548C2B72F0CFA03BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLossAbstract" xlink:label="loc_us-gaap_OperatingIncomeLossAbstract_7BD0CE58E0EF36C7663BB72F0CFA46C1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_38D37C1E8D2E9D48511DB72F0CF95E59" xlink:to="loc_us-gaap_OperatingIncomeLossAbstract_7BD0CE58E0EF36C7663BB72F0CFA46C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_84DB73500C812ADEF71DB72F0CFAE350" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingIncomeLossAbstract_7BD0CE58E0EF36C7663BB72F0CFA46C1" xlink:to="loc_us-gaap_OperatingIncomeLoss_84DB73500C812ADEF71DB72F0CFAE350" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_F4B7490086F9875024E682E5D6AB4770" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_4292DA4C32A8CE96E67182E5D6A4F464" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_F4B7490086F9875024E682E5D6AB4770" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_4292DA4C32A8CE96E67182E5D6A4F464" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_711AC3E94702EB5A545F82E5D6A544E7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_4292DA4C32A8CE96E67182E5D6A4F464" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_711AC3E94702EB5A545F82E5D6A544E7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_046450FDCE7D495D3C3482E5D6A5FF10_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_711AC3E94702EB5A545F82E5D6A544E7" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_046450FDCE7D495D3C3482E5D6A5FF10_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_046450FDCE7D495D3C3482E5D6A5FF10" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_711AC3E94702EB5A545F82E5D6A544E7" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_046450FDCE7D495D3C3482E5D6A5FF10" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_A209A1A533A2F5085B3482E5D6A5D5B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_046450FDCE7D495D3C3482E5D6A5FF10" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_A209A1A533A2F5085B3482E5D6A5D5B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_58ED3E686100BD51789082E5D6AAB9D0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_4292DA4C32A8CE96E67182E5D6A4F464" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_58ED3E686100BD51789082E5D6AAB9D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_89EED8011800AF9D1D1782E5D6AA59AA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_58ED3E686100BD51789082E5D6AAB9D0" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_89EED8011800AF9D1D1782E5D6AA59AA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_89EED8011800AF9D1D1782E5D6AA59AA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_58ED3E686100BD51789082E5D6AAB9D0" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_89EED8011800AF9D1D1782E5D6AA59AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_D9DA3BE4C0187708FDD782E5D6AA9836" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_89EED8011800AF9D1D1782E5D6AA59AA" xlink:to="loc_us-gaap_SalesRevenueNetMember_D9DA3BE4C0187708FDD782E5D6AA9836" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:label="loc_us-gaap_MajorCustomersAxis_187C30ACF1837F94001A82E5D6AB37E9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_4292DA4C32A8CE96E67182E5D6A4F464" xlink:to="loc_us-gaap_MajorCustomersAxis_187C30ACF1837F94001A82E5D6AB37E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_82C3B90E05C0498AF7B082E5D6AB151B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorCustomersAxis_187C30ACF1837F94001A82E5D6AB37E9" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_82C3B90E05C0498AF7B082E5D6AB151B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_82C3B90E05C0498AF7B082E5D6AB151B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorCustomersAxis_187C30ACF1837F94001A82E5D6AB37E9" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_82C3B90E05C0498AF7B082E5D6AB151B" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_USGovernmentMember" xlink:label="loc_ktos_USGovernmentMember_4D1D83F8790DAC61C33782E5D6AB72E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_82C3B90E05C0498AF7B082E5D6AB151B" xlink:to="loc_ktos_USGovernmentMember_4D1D83F8790DAC61C33782E5D6AB72E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_C7736361B99691622FED82E5D6ABE367" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_F4B7490086F9875024E682E5D6AB4770" xlink:to="loc_us-gaap_Revenues_C7736361B99691622FED82E5D6ABE367" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_D457376DEB0F9C6CFB4B82E5D6AB2B4C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_F4B7490086F9875024E682E5D6AB4770" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_D457376DEB0F9C6CFB4B82E5D6AB2B4C" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_41B4D0313BEED4825306B066D58254FC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_19ECD53F1D30A87D2BB2B066D581F447" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_41B4D0313BEED4825306B066D58254FC" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_19ECD53F1D30A87D2BB2B066D581F447" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_B80BBBEE909AB19189C1B066D58187CE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_19ECD53F1D30A87D2BB2B066D581F447" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_B80BBBEE909AB19189C1B066D58187CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_19974963FD2F5F04341EB066D5817034_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B80BBBEE909AB19189C1B066D58187CE" xlink:to="loc_us-gaap_EquityComponentDomain_19974963FD2F5F04341EB066D5817034_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_19974963FD2F5F04341EB066D5817034" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B80BBBEE909AB19189C1B066D58187CE" xlink:to="loc_us-gaap_EquityComponentDomain_19974963FD2F5F04341EB066D5817034" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_A5BBAF6C6E8746BFF619B066D5821E26" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_19974963FD2F5F04341EB066D5817034" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_A5BBAF6C6E8746BFF619B066D5821E26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8A67E471517651F2A859B066D582B6D5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_19974963FD2F5F04341EB066D5817034" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8A67E471517651F2A859B066D582B6D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_D453DED98E9F0709894CB066D582618C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_41B4D0313BEED4825306B066D58254FC" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_D453DED98E9F0709894CB066D582618C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_565EE6C1A5D12EA15292B066D5824027" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_41B4D0313BEED4825306B066D58254FC" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_565EE6C1A5D12EA15292B066D5824027" 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/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D09C4FCEBC0EC6DDE60B72F0D51CDA2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_884913812E57310A2618B72F0D51A88D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D09C4FCEBC0EC6DDE60B72F0D51CDA2" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_884913812E57310A2618B72F0D51A88D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_BFC7B36EE51BAF73FFE3B72F0D513CF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_884913812E57310A2618B72F0D51A88D" xlink:to="loc_us-gaap_RangeAxis_BFC7B36EE51BAF73FFE3B72F0D513CF9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_2ACE5B0E025A47DCC562B72F0D5110AA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_BFC7B36EE51BAF73FFE3B72F0D513CF9" xlink:to="loc_us-gaap_RangeMember_2ACE5B0E025A47DCC562B72F0D5110AA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_2ACE5B0E025A47DCC562B72F0D5110AA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_BFC7B36EE51BAF73FFE3B72F0D513CF9" xlink:to="loc_us-gaap_RangeMember_2ACE5B0E025A47DCC562B72F0D5110AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_20BD92D175FED98E4CB3B72F0D51BF03" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_2ACE5B0E025A47DCC562B72F0D5110AA" xlink:to="loc_us-gaap_MinimumMember_20BD92D175FED98E4CB3B72F0D51BF03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_B4909C56700195EABDA8B72F0D519FD0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_2ACE5B0E025A47DCC562B72F0D5110AA" xlink:to="loc_us-gaap_MaximumMember_B4909C56700195EABDA8B72F0D519FD0" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_FiscalYearDuration" xlink:label="loc_ktos_FiscalYearDuration_2080C131B7C3C91BBB50B72F0D51E60D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D09C4FCEBC0EC6DDE60B72F0D51CDA2" xlink:to="loc_ktos_FiscalYearDuration_2080C131B7C3C91BBB50B72F0D51E60D" xlink:type="arc" />
    <link:loc xlink:href="ktos-20170326.xsd#ktos_FiscalYearToDateDuration" xlink:label="loc_ktos_FiscalYearToDateDuration_EF42EF8380412F5FBF46B72F0D51B369" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_6D09C4FCEBC0EC6DDE60B72F0D51CDA2" xlink:to="loc_ktos_FiscalYearToDateDuration_EF42EF8380412F5FBF46B72F0D51B369" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.kratosdefense.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
</link:linkbase>
