Law, 24, made five birdies and one bogey in a final-round 67 to finish 17 under, having held a share of the lead throughout the tournament.

Sweden's Madelene Sagstrom, Canada's Brooke Henderson and Japan's Nasa Hataoka tied for second on 15 under.

"I believe in hard work and determination," said Law.

"I really stayed so focused out there today. Obviously my caddie, Jeff, did a great job keeping me calm."

Law's victory came three weeks after she lost in a play-off at the LPGA's Mediheal Championship.

"I guess after San Fran it really gave me perspective that I can compete at the top," she added.

"I came in this week with the sole intention of going one better. It feels really good."

Eight-time LPGA Tour winner Henderson made three birdies in the last round to finish tied for second alongside Sagstrom - who recorded her career-best finish - and Hataoka, who birdied the final hole.