diff --git a/pkg/services/authn/identity.go b/pkg/services/authn/identity.go
index 2b6e7bfe533..6e246114bcc 100644
--- a/pkg/services/authn/identity.go
+++ b/pkg/services/authn/identity.go
@@ -156,6 +156,9 @@ func (i *Identity) GetExtra() map[string][]string {
 	if i.GetOrgRole().IsValid() {
 		extra["user-instance-role"] = []string{string(i.GetOrgRole())}
 	}
+	if i.AccessTokenClaims != nil && i.AccessTokenClaims.Rest.ServiceIdentity != "" {
+		extra[authn.ServiceIdentityKey] = []string{i.AccessTokenClaims.Rest.ServiceIdentity}
+	}
 	return extra
 }
 
diff --git a/pkg/services/authn/identity_test.go b/pkg/services/authn/identity_test.go
new file mode 100644
index 00000000000..2a869d553c4
--- /dev/null
+++ b/pkg/services/authn/identity_test.go
@@ -0,0 +1,140 @@
+package authn
+
+import (
+	"testing"
+
+	authnlib "github.com/grafana/authlib/authn"
+	"github.com/grafana/authlib/types"
+	"github.com/grafana/grafana/pkg/services/org"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIdentity_GetExtra(t *testing.T) {
+	tests := []struct {
+		name     string
+		identity *Identity
+		expected map[string][]string
+	}{
+		{
+			name: "returns empty map when no extra fields are set",
+			identity: &Identity{
+				ID:   "1",
+				Type: types.TypeUser,
+			},
+			expected: map[string][]string{
+				"user-instance-role": {"None"},
+			},
+		},
+		{
+			name: "returns id-token when IDToken is set",
+			identity: &Identity{
+				ID:      "1",
+				Type:    types.TypeUser,
+				IDToken: "test-id-token",
+			},
+			expected: map[string][]string{
+				"id-token":           {"test-id-token"},
+				"user-instance-role": {"None"},
+			},
+		},
+		{
+			name: "returns user-instance-role when OrgRole is valid",
+			identity: &Identity{
+				ID:       "1",
+				Type:     types.TypeUser,
+				OrgID:    1,
+				OrgRoles: map[int64]org.RoleType{1: "Admin"},
+			},
+			expected: map[string][]string{
+				"user-instance-role": {"Admin"},
+			},
+		},
+		{
+			name: "returns service-identity when AccessTokenClaims contains ServiceIdentity",
+			identity: &Identity{
+				ID:   "1",
+				Type: types.TypeAccessPolicy,
+				AccessTokenClaims: &authnlib.Claims[authnlib.AccessTokenClaims]{
+					Rest: authnlib.AccessTokenClaims{
+						ServiceIdentity: "secrets-manager",
+					},
+				},
+			},
+			expected: map[string][]string{
+				string(authnlib.ServiceIdentityKey): {"secrets-manager"},
+				"user-instance-role":                {"None"},
+			},
+		},
+		{
+			name: "returns all extra fields when multiple are set",
+			identity: &Identity{
+				ID:       "1",
+				Type:     types.TypeUser,
+				OrgID:    1,
+				IDToken:  "test-id-token",
+				OrgRoles: map[int64]org.RoleType{1: "Editor"},
+				AccessTokenClaims: &authnlib.Claims[authnlib.AccessTokenClaims]{
+					Rest: authnlib.AccessTokenClaims{
+						ServiceIdentity: "custom-service",
+					},
+				},
+			},
+			expected: map[string][]string{
+				"id-token":                          {"test-id-token"},
+				"user-instance-role":                {"Editor"},
+				string(authnlib.ServiceIdentityKey): {"custom-service"},
+			},
+		},
+		{
+			name: "does not include service-identity when AccessTokenClaims is nil",
+			identity: &Identity{
+				ID:                "1",
+				Type:              types.TypeUser,
+				AccessTokenClaims: nil,
+			},
+			expected: map[string][]string{
+				"user-instance-role": {"None"},
+			},
+		},
+		{
+			name: "does not include service-identity when ServiceIdentity is empty",
+			identity: &Identity{
+				ID:   "1",
+				Type: types.TypeUser,
+				AccessTokenClaims: &authnlib.Claims[authnlib.AccessTokenClaims]{
+					Rest: authnlib.AccessTokenClaims{
+						ServiceIdentity: "",
+					},
+				},
+			},
+			expected: map[string][]string{
+				"user-instance-role": {"None"},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			extra := tt.identity.GetExtra()
+			assert.Equal(t, tt.expected, extra)
+		})
+	}
+}
+
+func TestIdentity_GetExtra_ServiceIdentityKey(t *testing.T) {
+	// Test that the ServiceIdentityKey constant matches authlib's constant
+	identity := &Identity{
+		ID:   "1",
+		Type: types.TypeAccessPolicy,
+		AccessTokenClaims: &authnlib.Claims[authnlib.AccessTokenClaims]{
+			Rest: authnlib.AccessTokenClaims{
+				ServiceIdentity: "test-service",
+			},
+		},
+	}
+
+	extra := identity.GetExtra()
+	require.Contains(t, extra, string(authnlib.ServiceIdentityKey))
+	assert.Equal(t, []string{"test-service"}, extra[string(authnlib.ServiceIdentityKey)])
+}