<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-09-10</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001175454</issuerCik>
        <issuerName>FLEETCOR TECHNOLOGIES INC</issuerName>
        <issuerTradingSymbol>FLT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001131656</rptOwnerCik>
            <rptOwnerName>SUMMIT VENTURES VI-A LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET</rptOwnerStreet1>
            <rptOwnerStreet2>18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001131666</rptOwnerCik>
            <rptOwnerName>SUMMIT VENTURES VI-B LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET</rptOwnerStreet1>
            <rptOwnerStreet2>18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001131279</rptOwnerCik>
            <rptOwnerName>SUMMIT VI ADVISORS FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SUMMIT PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>222 BERKELEY STREET, 18TH FLORR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001131280</rptOwnerCik>
            <rptOwnerName>SUMMIT VI ENTREPRENEURS FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SUMMIT PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>222 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001258822</rptOwnerCik>
            <rptOwnerName>SUMMIT INVESTORS VI LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SUMMIT PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>222 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001030825</rptOwnerCik>
            <rptOwnerName>SUMMIT SUBORDINATED DEBT FUND II L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SUMMIT PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>222 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001486421</rptOwnerCik>
            <rptOwnerName>Summit Partners Private Equity Fund VII-A, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET</rptOwnerStreet1>
            <rptOwnerStreet2>18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001385242</rptOwnerCik>
            <rptOwnerName>Summit Partners Private Equity Fund VII B L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET</rptOwnerStreet1>
            <rptOwnerStreet2>18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001435565</rptOwnerCik>
            <rptOwnerName>Summit Investors I, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001494616</rptOwnerCik>
            <rptOwnerName>Summit Investors I (UK), L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>222 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-09-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2000000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>104.86</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4132156</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares sold by the following entities: 1,136,477 shares of common stock sold by Summit Ventures VI-A, L.P., 473,957 shares of common stock sold by Summit Ventures VI-B, L.P., 23,636 shares of common stock sold by Summit VI Advisors Fund, L.P., 36,288 shares of common stock sold by Summit VI Entrepreneurs Fund, L.P., 9,516 shares of common stock sold by Summit Investors VI, L.P., 29,425 shares of common stock sold by Summit Subordinated Debt Fund II, L.P., 180,900 shares of common stock sold by Summit Partners Private Equity Fund VII-A, L.P., 108,651 shares of common stock sold by Summit Partners Private Equity Fund VII-B, L.P., 1,041 shares of common stock sold by Summit Investors I, LLC and 109 shares of common stock sold by Summit Investors I (UK), L.P.</footnote>
        <footnote id="F2">Represents shares held by the following entities: 2,348,053 shares of common stock held by Summit Ventures VI-A, L.P., 979,231 shares of common stock held by Summit Ventures VI-B, L.P., 48,833 shares of common stock held by Summit VI Advisors Fund, L.P., 74,975 shares of common stock held by Summit VI Entrepreneurs Fund, L.P., 19,660 shares of common stock held by Summit Investors VI, L.P., 60,795 shares of common stock held by Summit Subordinated Debt Fund II, L.P., 373,752 shares of common stock held by Summit Partners Private Equity Fund VII-A, L.P., 224,481 shares of common stock held by Summit Partners Private Equity Fund VII-B, L.P., 2,150 shares of common stock held by Summit Investors I, LLC and 226 shares of common stock held by Summit Investors I (UK), L.P.</footnote>
    </footnotes>

    <remarks>The entities mentioned in Footnotes 1 and 2 are collectively referred to as the &quot;Summit Entites.&quot; Each of the Summit Entities disclaims beneficial ownership of all shares except those specifically listed in the Footnotes as held by such entity, except to the extent of each such entity's pecuniary interest therein.</remarks>

    <ownerSignature>
        <signatureName>Summit Ventures VI-A, L.P., by Summit Partners VI (GP), L.P., its GP, by Summit Partners VI (GP), LLC, its GP, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Ventures VI-B, L.P., by Summit Partners VI (GP), L.P., Its GP, by Summit Partners VI (GP), LLC, Its GP, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph F. Trustey,  Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit VI Advisors Fund, L.P., by Summit Partners VI (GP), L.P., its GP, by Summit Partners VI (GP), LLC, its GP, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit VI Entrepreneurs Fund, L.P., by Summit Partners VI (GP), L.P., its GP, by Summit Partners VI (GP), LLC, its GP, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Investors VI, L.P., by Summit Partners VI (GP), L.P., its GP, by Summit Partners VI (GP), LLC, its GP, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Subordinated Debt Fund II,  L.P., by Summit Partners Subordinated Debt II, LLC, its GP, by Stamps, Woodsum &amp; Company IV, its GP, by Summit Partners, L.P., its GP, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners Private Equity Fund VII-A, L.P., by Summit Partners PE VII, L.P., its GP, by Summit Partners PE VII, LLC, its GP, by Summit Partners, L.P., its GP, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners Private Equity Fund VII-B, L.P., by Summit Partners PE VII, L.P., its GP, by Summit Partners PE VII, LLC, its GP, by Summit Partners, L.P., its GP, by Summit Master Company, LLC, its GP, by Robin W. Devereux, POA for Joseph Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Investors I, LLC, by Summit Investors Management, LLC, its Manager, by Summit Partners, L.P., its Managing Member, by Summit Master Company, LLC, its general partner, by Robin W. Devereux, POA for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Investors I (UK), L.P., by Summit Investors Management, LLC, its General Partner, by Summit Partners, L.P., its Managing Member, by Summit Master Company, its General Partner, by Robin W. Devereux, POA for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-09-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
