A new distinct cultivar of Osteospermum plant named `Sunny Antique Serena`, characterized by its unique color combinations on the upper and undersides of its ray florets: (upperside) when opening--RHS 5C to RHS 5D, yellow and when fully opened--RHS 11D, yellow; (underside) when opening and when fully opened--longitudinal stripes of alternating gray-orange colors, RHS N163A and RHS N163B, gray-orange; 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.