<SUBMISSION>
<ACCESSION-NUMBER>0001069258-08-000009
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20080407
<FILING-DATE>20080708
<DATE-OF-FILING-DATE-CHANGE>20080708
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>KRATOS DEFENSE & SECURITY SOLUTIONS, INC.
<CIK>0001069258
<ASSIGNED-SIC>4899
<IRS-NUMBER>133818604
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1228
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>4810 EASTGATE MALL
<STREET2>.
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92121
<PHONE>858-812-7300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>4810 EASTGATE MALL
<STREET2>.
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92121
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>WIRELESS FACILITIES INC
<DATE-CHANGED>19990817
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Bates Howard W.
<CIK>0001422668
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-27231
<FILM-NUMBER>08942816
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>317-506-7830
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>11405 N. PENNSYLVANIA STREET
<STREET2>SUITE 200
<CITY>CAMEL
<STATE>IN
<ZIP>46032
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-04-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001069258</issuerCik>
        <issuerName>KRATOS DEFENSE &amp; SECURITY SOLUTIONS, INC.</issuerName>
        <issuerTradingSymbol>KTOS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001422668</rptOwnerCik>
            <rptOwnerName>Bates Howard W.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>11405 N. PENNSYLVANIA STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>CAMEL</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46032</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Pres. Haverstick Cons. Div.</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-04-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>52784</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.8</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>403014</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares acquired by reporting person in connection with Issuer entering into a Settlement Agreement, Waiver and Release dated as of April 7, 2008, with the Shareholders' Representative, under the Agreement and Plan of Merger dated November 2, 2007 by and between Issuer, Kratos Government Solutions, Inc., Haverstick Acquisition Corporation and Haverstick Consulting, Inc. (the &quot;Merger Agreement&quot;), wherein Issuer agreed to issue additional shares of its common stock to the former Qualified Shareholders of Haverstick Consulting, Inc. as such term is defined in the Merger Agreement.</footnote>
        <footnote id="F2">Includes 350,230 shares previously reported on Form 4 dated January 7, 2008.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Howard W. Bates, by Matthew G. Colvin, Attorney-In-Fact</signatureName>
        <signatureDate>2008-07-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
