Kapalua's tour pro, Pressel closed with a 3-under 69 to edge Suzann Pettersen (69) by a stroke. Pressel finished at 8-under 280 and earned $225,000 for her second career win.
The 20-year-old Pressel birdied two of her final four holes and made a clutch 15-foot putt from the fringe near the front of the green to secure the victory.
She won the Kraft Nabisco Championship last year to become the youngest player in tour history to win a major. Pettersen tied for second in that event in California after faltering down the stretch.
Conditions at the scenic and hilly Bay Course were balmy and slightly breezy. The tradewinds were down considerably from the first three rounds.
Laura Diaz (70) finished third at 6 under. Angela Stanford (70), Sun Young Yoo (72) tied for fourth at 4 under, a stroke ahead of Stacy Lewis, who closed with a course-record 66, and Karin Koch (74).