diff --git a/internal/api/oidc/client.go b/internal/api/oidc/client.go
index ced270e54..6acd1486c 100644
--- a/internal/api/oidc/client.go
+++ b/internal/api/oidc/client.go
@@ -32,6 +32,10 @@ const (
 	ClaimResourceOwnerName          = ScopeResourceOwner + ":name"
 	ClaimResourceOwnerPrimaryDomain = ScopeResourceOwner + ":primary_domain"
 	ClaimActionLogFormat            = "urn:zitadel:iam:action:%s:log"
+	ScopeUserGroups                 = "groups"
+	ClaimUserGroups                 = ScopeUserGroups
+	ScopeCustomUserGroups           = "urn:zitadel:iam:user:groups"
+	ClaimCustomUserGroups           = ScopeCustomUserGroups
 
 	oidcCtx = "oidc"
 )
diff --git a/internal/api/oidc/client_converter.go b/internal/api/oidc/client_converter.go
index ec254e2fc..3253d92e4 100644
--- a/internal/api/oidc/client_converter.go
+++ b/internal/api/oidc/client_converter.go
@@ -271,5 +271,8 @@ func isScopeAllowed(scope string, allowedScopes ...string) bool {
 	if scope == ScopeProjectsRoles {
 		return true
 	}
+	if scope == ScopeCustomUserGroups || scope == ScopeUserGroups {
+		return true
+	}
 	return slices.Contains(allowedScopes, scope)
 }
diff --git a/internal/api/oidc/integration_test/userinfo_test.go b/internal/api/oidc/integration_test/userinfo_test.go
index b1b636869..e041d8721 100644
--- a/internal/api/oidc/integration_test/userinfo_test.go
+++ b/internal/api/oidc/integration_test/userinfo_test.go
@@ -30,6 +30,13 @@ func TestServer_UserInfo(t *testing.T) {
 	clientID, projectID := createClient(t, Instance)
 	addProjectRolesGrants(t, User.GetUserId(), projectID, roleFoo, roleBar)
 
+	// create user groups
+	group1 := Instance.CreateGroup(CTXIAM, t, Instance.DefaultOrg.GetId(), "group1")
+	group2 := Instance.CreateGroup(CTXIAM, t, Instance.DefaultOrg.GetId(), "group2")
+	// add the user to groups
+	Instance.AddUsersToGroup(CTXIAM, t, group1.GetId(), []string{User.GetUserId()})
+	Instance.AddUsersToGroup(CTXIAM, t, group2.GetId(), []string{User.GetUserId()})
+
 	tests := []struct {
 		name       string
 		prepare    func(t *testing.T, clientID string, scope []string) *oidc.Tokens[*oidc.IDTokenClaims]
@@ -154,6 +161,39 @@ func TestServer_UserInfo(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:    "custom group scope",
+			prepare: getTokens,
+			scope: []string{oidc.ScopeProfile, oidc.ScopeOpenID, oidc.ScopeEmail, oidc.ScopeOfflineAccess,
+				oidc_api.ScopeCustomUserGroups},
+			assertions: []func(*testing.T, *oidc.UserInfo){
+				assertUserinfo,
+				func(t *testing.T, info *oidc.UserInfo) {
+					expectedUserGroups := []map[string]interface{}{
+						{"id": group1.GetId(), "name": "group1"},
+						{"id": group2.GetId(), "name": "group2"},
+					}
+					userGroupsClaim := info.Claims[oidc_api.ClaimCustomUserGroups]
+					require.Len(t, userGroupsClaim, len(expectedUserGroups))
+					assert.ElementsMatch(t, expectedUserGroups, userGroupsClaim)
+				},
+			},
+		},
+		{
+			name:    "group scope",
+			prepare: getTokens,
+			scope: []string{oidc.ScopeProfile, oidc.ScopeOpenID, oidc.ScopeEmail, oidc.ScopeOfflineAccess,
+				oidc_api.ScopeUserGroups},
+			assertions: []func(*testing.T, *oidc.UserInfo){
+				assertUserinfo,
+				func(t *testing.T, info *oidc.UserInfo) {
+					expectedUserGroups := []string{"group1", "group2"}
+					userGroupsClaim := info.Claims[oidc_api.ClaimUserGroups]
+					require.Len(t, userGroupsClaim, len(expectedUserGroups))
+					assert.ElementsMatch(t, expectedUserGroups, userGroupsClaim)
+				},
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
diff --git a/internal/api/oidc/userinfo.go b/internal/api/oidc/userinfo.go
index 15ec5b21e..1ebbac581 100644
--- a/internal/api/oidc/userinfo.go
+++ b/internal/api/oidc/userinfo.go
@@ -190,6 +190,10 @@ func userInfoToOIDC(user *query.OIDCUserInfo, userInfoAssertion bool, scope []st
 			setUserInfoMetadata(user.Metadata, out)
 		case ScopeResourceOwner:
 			setUserInfoOrgClaims(user, out)
+		case ScopeCustomUserGroups:
+			setUserInfoCustomUserGroups(user.UserGroups, out)
+		case ScopeUserGroups:
+			setUserInfoUserGroups(user.UserGroups, out)
 		default:
 			if claim, ok := strings.CutPrefix(s, domain.OrgDomainPrimaryScope); ok {
 				out.AppendClaims(domain.OrgDomainPrimaryClaim, claim)
@@ -287,6 +291,24 @@ func setUserInfoRoleClaims(userInfo *oidc.UserInfo, roles *projectsRoles) {
 	}
 }
 
+func setUserInfoCustomUserGroups(userGroups []query.UserInfoUserGroup, out *oidc.UserInfo) {
+	if len(userGroups) == 0 {
+		return
+	}
+	out.AppendClaims(ClaimCustomUserGroups, userGroups)
+}
+
+func setUserInfoUserGroups(userGroups []query.UserInfoUserGroup, out *oidc.UserInfo) {
+	if len(userGroups) == 0 {
+		return
+	}
+	groups := make([]string, len(userGroups))
+	for i, userGroup := range userGroups {
+		groups[i] = userGroup.Name
+	}
+	out.AppendClaims(ClaimUserGroups, groups)
+}
+
 //nolint:gocognit
 func (s *Server) userinfoFlows(ctx context.Context, qu *query.OIDCUserInfo, userInfo *oidc.UserInfo, triggerType domain.TriggerType, clientID string) (err error) {
 	ctx, span := tracing.NewSpan(ctx)
diff --git a/internal/api/oidc/userinfo_test.go b/internal/api/oidc/userinfo_test.go
index 2646cc903..2bb8556b2 100644
--- a/internal/api/oidc/userinfo_test.go
+++ b/internal/api/oidc/userinfo_test.go
@@ -179,6 +179,16 @@ func Test_userInfoToOIDC(t *testing.T) {
 		Name:          "orgName",
 		PrimaryDomain: "orgDomain",
 	}
+	userGroups := []query.UserInfoUserGroup{
+		{
+			Name: "group1",
+			ID:   "group1-id",
+		},
+		{
+			Name: "group2",
+			ID:   "group2-id",
+		},
+	}
 	humanUserInfo := &query.OIDCUserInfo{
 		User: &query.User{
 			ID:                 "human1",
@@ -226,6 +236,7 @@ func Test_userInfoToOIDC(t *testing.T) {
 				UserResourceOwner: "org1",
 			},
 		},
+		UserGroups: userGroups,
 	}
 	machineUserInfo := &query.OIDCUserInfo{
 		User: &query.User{
@@ -503,6 +514,41 @@ func Test_userInfoToOIDC(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "human, scope custom user groups, found",
+			args: args{
+				user:  humanUserInfo,
+				scope: []string{ScopeCustomUserGroups},
+			},
+			want: &oidc.UserInfo{
+				Subject: "human1",
+				Claims: map[string]any{
+					ClaimCustomUserGroups: []query.UserInfoUserGroup{
+						{
+							Name: "group1",
+							ID:   "group1-id",
+						},
+						{
+							Name: "group2",
+							ID:   "group2-id",
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "human, scope user groups (group names), found",
+			args: args{
+				user:  humanUserInfo,
+				scope: []string{ScopeUserGroups},
+			},
+			want: &oidc.UserInfo{
+				Subject: "human1",
+				Claims: map[string]any{
+					ClaimUserGroups: []string{"group1", "group2"},
+				},
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
diff --git a/internal/query/projection/group.go b/internal/query/projection/group.go
index 5f25f13c3..d8d488926 100644
--- a/internal/query/projection/group.go
+++ b/internal/query/projection/group.go
@@ -51,6 +51,7 @@ func (g *groupProjection) Init() *old_handler.Check {
 		},
 			handler.NewPrimaryKey(GroupColumnInstanceID, GroupColumnID),
 			handler.WithIndex(handler.NewIndex("resource_owner", []string{GroupColumnResourceOwner})),
+			handler.WithIndex(handler.NewIndex("state", []string{GroupColumnState})),
 		),
 	)
 }
diff --git a/internal/query/userinfo.go b/internal/query/userinfo.go
index aa2920dfb..eaf52ec5e 100644
--- a/internal/query/userinfo.go
+++ b/internal/query/userinfo.go
@@ -82,10 +82,11 @@ func (q *Queries) GetOIDCUserInfo(ctx context.Context, userID string, roleAudien
 }
 
 type OIDCUserInfo struct {
-	User       *User          `json:"user,omitempty"`
-	Metadata   []UserMetadata `json:"metadata,omitempty"`
-	Org        *UserInfoOrg   `json:"org,omitempty"`
-	UserGrants []UserGrant    `json:"user_grants,omitempty"`
+	User       *User               `json:"user,omitempty"`
+	Metadata   []UserMetadata      `json:"metadata,omitempty"`
+	Org        *UserInfoOrg        `json:"org,omitempty"`
+	UserGrants []UserGrant         `json:"user_grants,omitempty"`
+	UserGroups []UserInfoUserGroup `json:"user_groups,omitempty"`
 }
 
 type UserInfoOrg struct {
@@ -94,6 +95,11 @@ type UserInfoOrg struct {
 	PrimaryDomain string `json:"primary_domain,omitempty"`
 }
 
+type UserInfoUserGroup struct {
+	ID   string `json:"id,omitempty"`
+	Name string `json:"name,omitempty"`
+}
+
 //go:embed userinfo_client_by_id.sql
 var oidcUserinfoClientQuery string
 
diff --git a/internal/query/userinfo_by_id.sql b/internal/query/userinfo_by_id.sql
index fec5bc968..99b8d1d16 100644
--- a/internal/query/userinfo_by_id.sql
+++ b/internal/query/userinfo_by_id.sql
@@ -62,6 +62,18 @@ user_org as (
 		join usr u on o.id = u.resource_owner
 	) r
 ),
+-- find the user's groups
+user_groups as (
+    select json_agg(row_to_json(r)) as user_groups from (
+        select g.id, g.name
+        from projections.group_users1 as gu
+            left join projections.groups1 as g on gu.group_id = g.id and gu.instance_id = g.instance_id
+        where gu.user_id = $1
+          and gu.instance_id = $2
+          and g.state = 1
+        )
+        r
+),
 -- join user grants to orgs, projects and user
 grants as (
 	select json_agg(row_to_json(r)) as grants from (
@@ -87,5 +99,6 @@ select json_build_object(
 	),
 	'org', (select organization from user_org),
 	'metadata', (select metadata from metadata),
-	'user_grants', (select grants from grants)
+	'user_grants', (select grants from grants),
+    'user_groups', (select user_groups from user_groups)
 );