The 22-year-old Kim birdied the final two holes of regulation to sign for a four-under 68, moving her to 12-under and into a play-off with China's Yu Liu and South Korean Yu Jin Sung, both of whom were also chasing their first LPGA win.

Kim hit a 3-wood for her second shot to the fringe of the par-5 18th green on the first play-off hole and then got up and up and down for birdie.

The victory came in only Kim's third start on the LPGA Tour since earning her full card last year via the secondary Epson Tour.

“I think just the birdie on 17 was definitely the big momentum changer,” Kim said. “Yeah, just kind of speechless right now. I will let you know that my second shot on that play-off hole, that wasn't intentional. I kind of got lucky there.

“So, yeah, I guess it was a good day after all.”

“I think just the birdie on 17 was definitely the big momentum changer. Yeah, just kind of speechless right now." - Grace Kim.

It will be a huge confidence boost for the Australian ahead of next week's first major of the year, the Chevron Championship in Texas, with Kim the second Australian winner of the tournament after Minjee Lee won in Hawaii in 2016.

Kim like Lee, is a former recipient of the Karrie Webb scholarship and paid tribute to the seven-time major winner after her victory.

“I mean, I don't think I have to say much. She's already helped me out so much from my amateur days. Yeah, I think this win is definitely a credit to her for sure,” Kim said of the Aussie legend.

Kim pocketed a winner's cheque of US$300,000 (A$447,000) and moved up 103 places to ninth in the Race to the CME Globe.

Peiyun Chien from Taiwan and Swede Linnea Strom tied for fourth one shot out of the play-off at 11-under.

Karis Davidson was the next best-placed Australian at Hoakalei Country Club on Saturday, finishing strongly with a 69 to move up to a tie for 19th at three-under.

Sarah Kemp (72) and Steph Kyriacou (73) were tied for 38th at even par, with Su Oh three shots further back.