Oh, with a 3-under-par 69, and Yani Tseng, who shot 72, finished regulation play deadlocked at 18-under 270 at the Panther Creek Country Club.

After Tseng missed a par putt on the first playoff hole, Oh sank a 1-footer for the win.

"I'm really happy," Oh said. "Today I was able to stay calm."

The winner's check was $255,000.

Na Yeon Choi (68) was third at 271. Shanshan Feng (63), Stacy Prammanasudh (69) and Hee-Won Han (71) shared fourth place.