Inbee Park claimed her 13th career
Park, who started the day with the same two-stroke lead, had birdies on Nos. 7 and 11 at Sentosa Golf Club to finish the tournament at 15-under 273, clear of 17-year-old Lydia Ko, who also shot a 70.
Park hasn't carded a bogey since the third round of the Honda LPGA Thailand, a streak of five consecutive bogey-free rounds.
"This week was just incredible," Park said. "I don't think I can even believe myself that I didn't make any bogeys for 72 holes. I mean, if I thought about bogeys, when am I going to make bogey; if I was afraid of the bogeys, I'd probably make bogeys. But I thought, whatever happens, it's just meant to be."
Stacy Lewis had a bogey on the final hole for a 72 that left her in third place, four strokes off the lead.
Azahara Munoz, who was runner-up last year, tied for fourth at 10-under with Shanshan Feng and So Yeon Ryu.
Defending champion Paula Creamer had a 74 to tie for 55th place.
Alex Cejka won the
The 44-year-old Czech-born German won in his 287th start on the PGA Tour. A four-time European Tour winner, he birdied four of the first six holes and finished with a three-under 69 in rainy, windy conditions at Trump International-Puerto Rico.
Sam Saunders, Arnold Palmer's grandson, had a chance to force another playoff hole, but his 8-foot birdie try on the par-five 18th went to the right. Jon Curran, Tim Petrovic and Argentina's Emiliano Grillo also were in the playoff.
Grillo and Curran shared the lead at eight under with one hole left in regulation, but closed with bogeys in the second-to-last group. Grillo settled for a 70 after missed a short putt. Curran also had a 70. Petrovic shot a 67, and Saunders had a 68.
Trevor Fisher Jr. finished with a 64 to win the Africa Open by five shots for his first European Tour title.
The South African had nine birdies and a single bogey in his final round to finish on 24-under 264 overall, well clear of England's Matt Ford (67) in second, in East London, South Africa.
Eduardo de la Riva, Jorge Campillo and Morten Orum Madsen were a further three shots behind Ford at East London Golf Club.
Fisher Jr. had a two-shot overnight lead over Ford, who stayed in contention in the final round until a two-shot swing at No. 9, where Fisher made birdie and Ford made bogey.