It was Pettersen's 10th LPGA title and second in two weeks. She beat Catriona Matthew in a playoff Oct. 21 in winning the tournament in South Korea.
Her final-round 69 included five birdies and a pair of bogeys that allowed her to make up a two-stroke deficit to Inbee Park, who had three bogeys in a 2-over 74 Sunday.
Pettersen was 19-under 269 for the tournament while Park ended up at 16-under. World No. 1 and tournament defending champion Yani Tseng was third at 15-under after a final-round 71. Matthew was 2-under in the final round for a 72-hole total of 14-under.
A birdie by Pettersen at the first hole and bogey at No. 5 by Park created a tie for first. Both players had birdies at 6 and bogeys at the seventh hole. Pettersen's bogey at 11 returned the lead to Park but Pettersen pulled even with a birdie at the 12th.
Park slipped to bogey at 14 and Pettersen pulled further ahead with a birdie at 15. Park had pars at the last three holes and Pettersen sealed the win with a birdie at the par-5 18th.