A new distinct cultivar of Osteospermum plant named `Sunny Golden Serena`, characterized by its unique gray-orange color combination of upper and underside of ray florets: (when opening) upperside RHS 163D with stripes of RHS 164B and underside RHS N163 with stripes of RHS 165A; (fully opened) upperside RHS 164D with stripes of RHS 164A and underside center stripe RHS 165B with margins RHS 164C; upright, compact and globular plant habit; dense and bushy growth habit, mainly due to upright stems; moderately vigorous growth habit, but less need for chemical growth retardation; and high number of inflorescences per plant.