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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-06-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001397911</issuerCik>
        <issuerName>LPL Financial Holdings Inc.</issuerName>
        <issuerTradingSymbol>LPLA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001495741</rptOwnerCik>
            <rptOwnerName>TPG Group Holdings (SBS) Advisors, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC,</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</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>0000860866</rptOwnerCik>
            <rptOwnerName>BONDERMAN DAVID</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC,</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</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>0001099776</rptOwnerCik>
            <rptOwnerName>COULTER JAMES G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC,</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</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, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2013-06-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>529702</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21418756</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Explanation of Responses</value>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2013-06-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>79908</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>36.6316</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21338848</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Explanation of Responses</value>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2013-06-13</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>57818</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>36.6663</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21281030</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Explanation of Responses</value>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Effective June 12, 2013, each of TPG Management IV-A, L.P., TPG Equity IV-A, L.P., TPG FOF IV-QP, L.P. and TPG GenPar IV, L.P. (&quot;GenPar IV&quot;) distributed shares of Common Stock (each, a &quot;Share&quot;) of LPL Financial Holdings Inc. (the &quot;Issuer&quot;) pro rata to their respective partners.</footnote>
        <footnote id="F2">On each of June 12 and 13, 2013, each of TPG Associates IV, L.P., TPG Coinvestment IV, L.P., and TPG Partners IV, L.P. (&quot;Partners IV&quot;) sold Shares pursuant to Rule 144 under the Securities Act of 1933, as amended.</footnote>
        <footnote id="F3">The number of securities reported represents an aggregate number of Shares sold in multiple open market transactions over a range of sale prices.  The price reported represents the weighted average price.  Sale prices range from $36.28 to $36.845 per Share, inclusive. The Reporting Persons (as defined below) undertake to provide the staff of the SEC, the Issuer, or a stockholder of the Issuer, upon request, the number of Shares sold by the Reporting Persons at each separate price within the range.</footnote>
        <footnote id="F4">The number of securities reported represents an aggregate number of Shares sold in multiple open market transactions over a range of sale prices. The price reported represents the weighted average price. Sale prices range from $36.35 to $36.785 per Share, inclusive. The Reporting Persons undertake to provide the staff of the SEC, the Issuer, or a stockholder of the Issuer, upon request, the number of Shares sold by the Reporting Persons at each separate price within the range.</footnote>
        <footnote id="F5">David Bonderman and James G. Coulter are officers and sole shareholders of TPG Group Holdings (SBS) Advisors, Inc. (&quot;Group Advisors&quot; and, together with Messrs. Bonderman and Coulter, the &quot;Reporting Persons&quot;), which is the general partner of TPG Group Holdings (SBS), L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Holdings I, L.P. (&quot;Holdings I&quot;), which holds 424,827 Shares and is the sole member of TPG GenPar IV Advisors, LLC, which is the general partner of GenPar IV, which is the general partner of Partners IV, which holds 20,710,185 Shares.</footnote>
        <footnote id="F6">As a result of the transactions disclosed herein and excluding the Shares held by Holdings I and Partners IV (the &quot;TPG Shareholders&quot;), Mr. Bonderman holds directly or indirectly 127,917 Shares and Mr. Coulter holds directly or indirectly 18,101 Shares.</footnote>
        <footnote id="F7">Because of the Reporting Persons' respective relationships to the TPG Shareholders, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of such TPG Shareholders.  Each Reporting Person disclaims beneficial ownership of the Shares, except to the extent of such Reporting Person's pecuniary interest therein, if any.</footnote>
        <footnote id="F8">Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the &quot;Exchange Act&quot;), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities beneficially owned in excess of their respective pecuniary interests.</footnote>
    </footnotes>

    <remarks>(9) The Reporting Persons are jointly filing this Form 4 pursuant to Rule 16a-3(j) under the Exchange Act.

(10) Ronald Cami is signing on behalf of both Messrs. Bonderman and Coulter pursuant to authorization and designation letters dated July 1, 2010, which were previously filed with the Securities and Exchange Commission.</remarks>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami on behalf of David Bonderman (9) (10)</signatureName>
        <signatureDate>2013-06-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami on behalf of James G. Coulter (9) (10)</signatureName>
        <signatureDate>2013-06-14</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami, Vice President, TPG Group Holdings (SBS) Advisors, Inc. (9)</signatureName>
        <signatureDate>2013-06-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
