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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-03-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000731766</issuerCik>
        <issuerName>UNITEDHEALTH GROUP INC</issuerName>
        <issuerTradingSymbol>UNH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001180162</rptOwnerCik>
            <rptOwnerName>HEMSLEY STEPHEN J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O UNITEDHEALTH GROUP INCORPORATED</rptOwnerStreet1>
            <rptOwnerStreet2>1 HEALTH DRIVE</rptOwnerStreet2>
            <rptOwnerCity>EDEN PRAIRIE</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55344</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-03-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>31</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>706819.942</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>343.0767</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>318200</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trusts</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents dividend equivalents paid on vested deferred stock units. The dividend equivalents are immediately vested and are subject to the same terms as the underlying deferred stock units.</footnote>
        <footnote id="F2">Excludes 200,000 shares previously owned directly which were contributed to the reporting person's trusts, in the amounts of 100,000 on February 7, 2025, and 100,000 on February 27, 2025, respectively. These contributions were exempt from reporting pursuant to Rule 16a-13.</footnote>
        <footnote id="F3">Reflects the reporting person's holdings of 200,000 shares previously owned directly which were contributed to the reporting person's trusts, in the amounts of 100,000 on February 7, 2025 and 100,000 on February 27, 2025, respectively, and 118,200 shares previously reported as held in Grantor Retained Annuity Trusts.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Faraz A. Choudhry, Attorney-in-Fact for Stephen J. Hemsley</signatureName>
        <signatureDate>2025-03-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "wk-form4_1742506144.xml", "description": "FORM 4", "secsgml_size_bytes": 5433}]
X0508
4
2025-03-18
0
0000731766
UNITEDHEALTH GROUP INC
UNH
0001180162
HEMSLEY STEPHEN J
C/O UNITEDHEALTH GROUP INCORPORATED
1 HEALTH DRIVE
EDEN PRAIRIE
MN
55344
1
0
0
0
0
Common Stock
2025-03-18
4
A
0
31
0
A
706819.942
D
Common Stock
343.0767
I
By 401(k)
Common Stock
318200
I
By Trusts
Represents dividend equivalents paid on vested deferred stock units. The dividend equivalents are immediately vested and are subject to the same terms as the underlying deferred stock units.
Excludes 200,000 shares previously owned directly which were contributed to the reporting person's trusts, in the amounts of 100,000 on February 7, 2025, and 100,000 on February 27, 2025, respectively. These contributions were exempt from reporting pursuant to Rule 16a-13.
Reflects the reporting person's holdings of 200,000 shares previously owned directly which were contributed to the reporting person's trusts, in the amounts of 100,000 on February 7, 2025 and 100,000 on February 27, 2025, respectively, and 118,200 shares previously reported as held in Grantor Retained Annuity Trusts.
Faraz A. Choudhry, Attorney-in-Fact for Stephen J. Hemsley
2025-03-20