Ariya frittered away a seven-shot lead with nine holes remaining before parring the fourth playoff hole to edge South Korea's Kim Hyo-joo and become the first player from Thailand to lift the trophy.
The 22-year-old from Thailand carried a four-stroke lead into the final round, but needed a play-off to overcome Kim Hyo-joo.
With Jutanugarn and Kim finishing a two-hole aggregate playoff at even par and each parring the first sudden-death hole, Jutanugarn got up-and-down from a greenside bunker on the par-4 18th.
Anyone who watched surely enjoyed the affair, and they may also have been clued into a specific visual: Jutanugarn applauding successful shots made by Kim during their one-on-one playoff. Jutanugarn, already a nine-time victor on the LPGA Tour and the 2016 British Open champion, appeared under no pressure whatsoever when beginning her final nine holes.
She made a almost ideal bunker shot to within a foot of the cup on the tournament-clinching hole, beating South Korea's Hyo-Joo Kim, who shot a 5-under 67 in the final round to force the playoff.
Kiwi Lydia Ko has finished tied for 50th at nine-over, after a one-over final round.
"I feel very good about how I played, especially that I did not have a bogey today in the final round".
"Actually, I wasn't keeping up with the score at the time so I didn't really know about it".
"I felt pretty good", Jutanugarn said of facing that decisive sand shot. I think I rushed putting them in.
"On 10 I didn't feel comfortable to hit three-wood and honestly I should't hit 3-wood but I did", she said after the round.
"After you have seven-shot lead and end up in playoff, I had no expectation because I kind of got mad a little bit with my back nine". However, she carded a triple bogey at No. 10, then a bogey at No. 12.
Jutanugarn had to play 28 holes after the second round was suspended due to risky weather on Friday but the Thai star managed to end the day atop the leaderboard, ahead of Sarah Jane Smith at 12 under following a 67.
Smith, who is ranked 97th in the world, has put on an impressive performance this week after she switched back to a old set of clubs.
With Jutanagarn advancing, Smith finally stumbled with back to back bogeys at the eighth and ninth holes to go with her 16 pars in a two-over 74 as her challenger shot 67 to take command.
"I knew from the start it was going to be tight, " said Olesen, who entered the final round tied with Molinari one stroke behind Lee Slattery.
On Monday at the CME Group Tour Championship last November, Jutanguarn told Nilsson and Marriott that it cost $350 to educate a child for an entire year at the schools she helps to fund.
"It was tough because I started thinking about the outcome and tried to play good".
"I've kind of been playing a little bit better since San Francisco so it's just been like gradually a little bit getting better", said Oh who finished 4th at her last start in MI.
Smith now sits four shorts clear of fellow Australian Oh Su-Hyun.