Ko, who became the youngest winner in LPGA Tour history when she won the 2012 Canadian event at age 15, finished this year's tourney at 15-under-par 265.
She became the first player in nearly two years to successfully defend an LPGA crown.
Karine Icher (67) finished second at 10-under.
Third-round leader Caroline Hedwall (71) and Brittany Lincicome (69) tied for third at 9-under.
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'
Kate Middleton recycles dress at movie premiere