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

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-03-13</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>2012-03-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4000000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>36.02</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19040170</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: 2,272,957 shares of common stock sold by Summit Ventures VI-A, L.P., 947,913 shares of common stock sold by Summit Ventures VI-B, L.P., 47,271 shares of common stock sold by Summit VI Advisors Fund, L.P., 72,577 shares of common stock sold by Summit VI Entrepreneurs Fund, L.P., 19,032 shares of common stock sold by Summit Investors VI, L.P., 58,850 shares of common stock sold by Summit Subordinated Debt Fund II, L.P., 361,798 shares of common stock sold by Summit Partners Private Equity Fund VII-A, L.P., 217,302 shares of common stock sold by Summit Partners Private Equity Fund VII-B, L.P., 2,082 shares of common stock sold by Summit Investors I, LLC and 218 shares of common stock sold by Summit Investors I (UK), L.P.</footnote>
        <footnote id="F2">Represents shares held by the following entities: 10,819,367 shares of common stock sold by Summit Ventures VI-A, L.P., 4,512,109 shares of common stock sold by Summit Ventures VI-B, L.P., 225,013 shares of common stock sold by Summit VI Advisors Fund, L.P., 345,470 shares of common stock sold by Summit VI Entrepreneurs Fund, L.P., 90,592 shares of common stock sold by Summit Investors VI, L.P., 280,130 shares of common stock sold by Summit Subordinated Debt Fund II, L.P., 1,722,176 shares of common stock sold by Summit Partners Private Equity Fund VII-A, L.P., 1,034,365 shares of common stock sold by Summit Partners Private Equity Fund VII-B, L.P., 9,909 shares of common stock sold by Summit Investors I, LLC and 1,039 shares of common stock sold by Summit Investors I (UK), L.P.</footnote>
    </footnotes>

    <remarks>The entities mentioned in Footnote 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.; (i) 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. (i) 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 (ii) 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 its Investment Committee, composed of Martin J. Mannion and Bruce R. Evans, has voting and dispositive authority over the shares held by each of these entities and therefore beneficially owns such shares.  Each of the Summit Entities, Mr. Mannion and Mr. Evans disclaim beneficial ownership of the shares, and this report shall not be deemed an admission that the Reporting Persons are the beneficial owners of the shares for the purpose of Section 16 or for any other purpose, except, in each case, to the extent of each such Reporting Person's pecuniary interest therein.</remarks>

    <ownerSignature>
        <signatureName>Summit Partners, L.P., by Summit Master Company, LLC, Its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2012-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Stamps, Woodsum &amp; Co. IV, by Summit Partners, L.P., its General Partner, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2012-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Investors Management, 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>2012-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>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>2012-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>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>2012-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners SD II, LLC, by Summit Partners, L.P., its General Partner, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2012-03-13</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 General Partner, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2012-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Summit Partners VI (GP), LLC, by Summit Partners, L.P., its General Partner, by Summit Master Company, LLC, its General Partner, by Robin W. Devereux, Power of Attorney for Joseph F. Trustey, Member</signatureName>
        <signatureDate>2012-03-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Robin W. Devereux, Power of Attorney for Martin J. Mannion</signatureName>
        <signatureDate>2012-03-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
