Jin Young Ko wins the tournament by two strokes over Nelly Korda, with Ayaka Furue and two others one shot further back in Singapore.
Runner-up Mone Inami wins a playoff with Lydia Ko to capture Japan's first medal in Olympic golf.
Japan adds to its national record-breaking medal haul with silver and bronze in the men’s 20-km race walk.
Defending champion Inbee Park is three strokes back, while Japan's Nasa Hataoka is tied for 16th.