Ko, 17, went bogey-free on the final day, sinking six birdies to emerge triumphant at 15 under overall at the Highland Meadows Golf Club.
The South Korean-born golfer, who overturned a two-shot deficit at the start of play to earn her fourth LPGA Tour title and second of the year, finished a stroke clear of 2012 champion Ryu So Yeon.
South Korea's Ryu also enjoyed a bogey-free round - her second of the tournament - firing a 67 as she earned second spot.
A shot further back was American Cristie Kerr (67), who earned sole possession of third place.
Kerr birdied her opening two holes and had five in total as she finished three shots adrift of Ko.
Malaysian Kelly Tan (67), Australia's Katherine Kirk (68) and South African Lee-Anne Pace (71) were in a three-way tie for fourth at 11 under.
Swede Pernilla Lindberg (65) finished with a flurry, birdying her final four holes as she climbed to seventh spot.
Julieta Granada (66) of Paraguay, American pair Kris Tamulis (68) and Mo Martin (69), and Australian Lindsey Wright (68) were also at 10 under.
Meanwhile, defending champion and Spaniard Beatriz Recari was nine shots off the pace after carding a 70 in the final round.