After driving into the water in regulation on the par-4 18th, Kim forced the playoff with an 18-foot chip-in for par. She then won on the hole with her 8-iron shot that barely cleared the water.
The 22-year-old South Korean player became the first two-time winner on the LPGA Tour this year. She won in the Bahamas in February in her second start as a tour member.
Kim rebounded from a disappointing final round two weeks ago in the ANA Inspiration when she squandered the lead and ended up tying for fourth.
She closed with a 1-over 73 in wind gusting to 30 mph at Ko Olina to match Park at 11-under 277. Park finished with a 71.
I.K. Kim bogeyed the final two holes for a 74 that left her two strokes back.