The Norwegian won her 11th LPGA Tour title on the first hole of the play-off after the American - born to Mexican immigrant parents - sent her approach into the water.
Pettersen led after rounds two and three but was forced into a play-off after bogeying at the last in the final round to finish with a 5-under 67 and finish on 19-under.
Salas came from five strokes behind to shoot a tournament-record 62 following earlier rounds of 69, 71 and 67.
"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.
"My game has been feeling great. It's nice that I have kept kind of the progress that I had from Kraft."
Salas double bogeyed the play-off hole after that disastrous chunk shot.
"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 suffered a collapse a fortnight ago at the Kraft Nabisco Championship, closing with a 79 to tie for 25th having sat three strokes behind leader - and eventual winner - Inbee Park after round three.
"From shooting a 79 at Kraft to shooting a 62 here in Hawaii... I can't really describe the feeling," she said. "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."
Pettersen was surprised to see Salas closing on her.
"I birdied 15, and then I think I was aware that she was like 18 under," Pettersen said. "So I mean, she wasn't going anywhere, and I'm like, 'Oh, my God, where did she start this day? Because I didn't remember seeing her next to my name on the list yesterday.
"She's a tough cookie. She's been playing fantastic. She's just got to keep putting herself in this position, and she'll get her win."
Thail17-year-old Ariya Jutanugarn finished third, four strokes behind the leaders, after shooting a 66.
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