Choi, who had a two-stroke lead heading into the final round, lost her spot atop the leaderboard early on as defending champion Stacy Lewis made three birdies on the front nine. Choi's front nine on the other hand consisted of a bogey of the sixth and eight pars.
The 27-year-old continued to trail Lewis by one stroke with three holes to play, but finally took the lead in dramatic fashion as she made an eagle on the par-four 16th.
Choi then proceeded to clinch her ninth LPGA Tour title with a birdie on the 17th, while Lewis faltered as she missed two fairly simple birdie putts on the 16th and 17th which would have seen her retake the lead.
To add insult to injury, Lewis ended her round with a bogey on the 18th to finish tied third with Azahara Munoz and Anna Nordqvist.
Meanwhile, Japan's Mika Miyazato made a late run for the title as she made three birdies on her front nine. But, she suffered a setback on the par-four 13th as she registered a double bogey.
Despite going on to record consecutive birdies on the 16th and 17th, Miyazato fell two strokes short of Choi.
World number two Lydia Ko bounced back from two disappointing rounds with a spectacular final-round 63, which consisted of eight birdies, including three in a row from the first to the third hole. As a result of her superb round, Ko finished tied sixth on the leaderboard with Paula Creamer and Minjee Lee.