Kim was beaten on the first playoff hole by Yoo Sun-young at the tournament after both finished the fourth round with 3-under-par 69s and were 9-under for 72 holes. That boosted them past Yani Tseng and led to the playoff.
Yoo managed a birdie at the par-5 18th hole while Kim had a par in the playoff.
The win, her second on the LPGA Tour, moved Yoo from 2nd t no. 15 in the world rankings. Kim, however, moves from 12th to No. 5.
Tseng, with a rankings average of 18.64, has been No. 1 for 59 weeks. Only Lorena Ochoa (158 weeks) and Annika Sorenstam (60) have been No. 1 for more weeks.
Kim's average is 6.93. Ahn Sun-ju (6.58) drops one place to sixth ahead of No. 7 Ai Miyazato (6.51). Jiyai Shin slips from sixth to No. 8, even though she technically has the same average as Miyazato. Stacy Lewis (6.48) remains ninth and Paula Creamer (6.31) goes from eighth to No. 10.