Pettersen, the leader after the second and third rounds at Ko Olina, bogeyed the final hole of regulation to set up the playoff on the par-4 18th. The 32-year-old Norwegian closed with 5-under-par 67, and Salas had a tournament-record 62 to finish at 19-under 269.
"I thought 20 was going to do it," Pettersen said. "That would take a fantastic round from anyone behind me, and it would take some good golf from me, but that was kind of the number I was shooting for."
Salas had a double bogey on the playoff hole. She played a nine-hole stretch in 9 under, birdieing Nos. 8-9, holing out from 169 yards with a 6-iron for eagle on the par-4 10th and adding birdies on Nos. 12-16.
"Chunk is not bad, but if you have water it's really bad," Salas said. "But I still had a chance, and that putt didn't go in. Not everything is going to fall, but I played my butt off today."
The 23-year-old American was coming off a devastating collapse two weeks ago in the Kraft Nabisco Championship when she closed with 79 to tie for 25th after beginning the final round three strokes behind playing partner and eventual winner Inbee Park.
"From shooting a 79 at Kraft to shooting a 62 here in Hawaii, like that just - I can't really describe the feeling, just I feel so proud of myself to put that 79 in the back of my mind and just to go out and play some golf," Salas said. "I took a big risk in using the short putter, but I felt extremely comfortable. I felt like me again."
Pettersen won her 11th LPGA Tour title. She had consecutive LPGA Tour victories late last season in South Korea and Taiwan and won a Ladies European Tour event last month in China.
"My game has been feeling great," Pettersen said. "It's nice that I have kept kind of the progress that I had from Kraft."
CHAMPIONS TOUR: In Duluth, Ga., Esteban Toledo, a rookie looking for his first win on the Champions Tour, has a one-stroke lead heading into the final round of the Greater Gwinnett Championship.
Toledo, from Mexicali, Mexico, completed his first-round 68 early Saturday before shooting 2-under-par 70 in the second round. Bernhard Langer had 66 that left him in a four-way tie for second.
Langer is tied with Roger Chapman, Tom Pernice Jr. and Mark Calcavecchia.
Michael Allen took the first-round lead by completing his 67 early Saturday. He lost the lead in the second round when he called a two-stroke penalty on himself for removing an embedded pine cone on No. 4.
Allen added another double bogey on No. 5 before recovering for 73 that left him 4-under and two strokes behind the leader.
Augusta native Larry Mize shot 75 and is nine back at 147. Former Augusta resident Allen Doyle had 72 and is at 152.
EUROPEAN TOUR: In Valenica, Spain, Mark Warren shot 4-under-par 68 to take a two-shot lead after the third round of the Spanish Open.
Warren had six birdies to go with two bogeys on the Parador de El Saler course.
to move to the top of the leaderboard with 8-under 208.
Craig Lee is two strokes back after 70, with English pair David Horsey (66) and Paul Waring (69) another shot behind.
American Peter Uihlein led entering the day but only managed 74 to fall four shots back.
Sergio Garcia is seven shots off the lead after 70.