Having started the day three strokes back from the lead, Yin pumped her fist with satisfaction as she drained a birdie putt on the par-five 18, carding a four-under-par 67, before waiting for her competitors to finish in Springfield, New Jersey.
Yin, who collected her maiden LPGA Tour title at the DIO Implant LA Open earlier this year, is only the second Chinese woman to win a golf major.
Japan's Yuka Saso finished one stroke back in second place after a bogey on the par-three 16 undermined an otherwise blemish-free final round.