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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-03-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000830588</rptOwnerCik>
            <rptOwnerName>SUMMIT PARTNERS 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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Manager of GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001032076</rptOwnerCik>
            <rptOwnerName>STAMPS WOODSUM &amp; CO IV</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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Indirect GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001507545</rptOwnerCik>
            <rptOwnerName>Summit Investors Management, 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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Manager of GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001486418</rptOwnerCik>
            <rptOwnerName>Summit Partners PE VII, 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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001486419</rptOwnerCik>
            <rptOwnerName>Summit Partners PE VII, LLC</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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Indirect GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001032090</rptOwnerCik>
            <rptOwnerName>SUMMIT PARTNERS SD II LLC</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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001258826</rptOwnerCik>
            <rptOwnerName>SUMMIT PARTNERS VI GP 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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001258825</rptOwnerCik>
            <rptOwnerName>SUMMIT PARTNERS VI GP LLC</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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Indirect GP of 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001018067</rptOwnerCik>
            <rptOwnerName>MANNION MARTIN J</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>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Manager of GP of 10% owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-03-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1500000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>70.55</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8632156</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See remarks.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares sold by the following entities: 852,358 shares of common stock sold by Summit Ventures VI-A, L.P., 355,468 shares of common stock sold by Summit Ventures VI-B, L.P., 17,727 shares of common stock sold by Summit VI Advisors Fund, L.P., 27,216 shares of common stock sold by Summit VI Entrepreneurs Fund, L.P., 7,137 shares of common stock sold by Summit Investors VI, L.P., 22,069 shares of common stock sold by Summit Subordinated Debt Fund II, L.P., 135,674 shares of common stock sold by Summit Partners Private Equity Fund VII-A, L.P., 81,488 shares of common stock sold by Summit Partners Private Equity Fund VII-B, L.P., 781 shares of common stock sold by Summit Investors I, LLC and 82 shares of common stock sold by Summit Investors I (UK), L.P.</footnote>
        <footnote id="F2">Represents shares held by the following entities: 4,905,127 shares of common stock held by Summit Ventures VI-A, L.P., 2,045,634 shares of common stock held by Summit Ventures VI-B, L.P., 102,013 shares of common stock held by Summit VI Advisors Fund, L.P., 156,624 shares of common stock held by Summit VI Entrepreneurs Fund, L.P., 41,071 shares of common stock held by Summit Investors VI, L.P., 127,002 shares of common stock held by Summit Subordinated Debt Fund II, L.P., 780,776 shares of common stock held by Summit Partners Private Equity Fund VII-A, L.P., 468,946 shares of common stock held by Summit Partners Private Equity Fund VII-B, L.P., 4,492 shares of common stock held by Summit Investors I, LLC and 471 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 Entities.&quot;  Summit Partners, L.P. is (i) the managing member of Summit Partners VI (GP), LLC, which is the general partner of Summit Partners VI (GP), L.P., which is the general partner of Summit Ventures VI-A, L.P., Summit Ventures VI-B, L.P., Summit VI Advisors Fund, L.P., Summit VI Entrepreneurs Fund, L.P. and Summit Investors VI, L.P.; (ii) the managing member of Stamps, Woodsum Co. IV,  which is the general partner of Summit Partners SD, LLC, which is the general partner of Summit Subordinated Debt Fund II, L.P.; (iii) the managing member of Summit Partners PE VII, LLC, which is the general partner of Summit Partners PE VII, L.P., which is the general partner of Summit Partners Private Equity Fund VII-A, L.P. and Summit Partners Private Equity Fund VII-B, L.P.; and (iiv) the managing member of Summit Investors Management, LLC, which is the manager of Summit Investors I, LLC., and the general partner of Summit Investors I (UK), L.P. Summit Partners, L.P., through a three-person investment committee currently composed of Bruce R. Evans, Martin J. Mannion and Peter Y. Chung, has voting and dispositive authority over the shares held by the Summit Entities, and therefore may beneficially own such shares. Each of the Summit Entities, Mr. Evans, Mr. Mannion and Mr. Chung disclaim beneficial ownership of the shares, except, in each case, to the extent of such person or entity's pecuniary interest therein.</remarks>

    <ownerSignature>
        <signatureName>Summit Partners, L.P., by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, POA for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Stamps, Woodsum &amp; Co. IV, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Investors Management, LLC, by Summit Partners, L.P., its Managing Member, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, POA for Joseph Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners PE VII, L.P., by Summit Partners PE VII, LLC, its General Partner, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, POA for Joseph Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners PE VII, LLC, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its General Parnter, by Robin W. Devereux, POA for Joseph Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners SD II, LLC, by Stamps, Woodsum &amp; Co. IV, its General Partner, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners VI (GP), L.P., by Summit Partners VI (GP), LLC, its General Partner, by Summit Partners L.P., its Manager, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners VI (GP), LLC, by Summit Partners, L.P., its Manager, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Robin W. Devereux, POA for Martin J. Mannion</signatureName>
        <signatureDate>2013-03-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
