Thompson was playing in her third event since her stunning defeat at the ANA Inspiration, when she was hit with a four-shot penalty during the final round and eventually lost in a playoff in the year's first major.
The 22-year-old American never gave her opponents an opening on Sunday. Starting her round three shots ahead of the field, Thompson recorded six birdies in her bogey-free round, including a pair at Nos. 1 and 3 to pad her lead.
Thompson, ranked fifth in the Rolex World Rankings, notched her first victory on the LPGA Tour since the 2016 Honda LPGA Thailand.
Chun also got off to a fast start with three birdies in the first seven holes to whittle the deficit to two shots, but Thompson birdied No. 9 and added birdies at the 12th, 14th and 15th to pull away.
It was the third runner-up finish of the season for Chun, whose bogey-free 67 left her four shots in front of the third-place finisher Angela Stanford.
Stanford had four birdies and an eagle, at the par-5 15, in her closing round of 66 to finish one shot ahead of Danielle Kang, who finished alone in fourth place at 10-under 274.
Carlota Ciganda of Spain carded a 67 to finish in a tie for fifth with Sei Young Kim (71) of South Korea at 275.
Americans Ryann O'Toole (69) and Gerina Piller (69) were another shot back in a tie for seventh with Sweden's Madelene Sagstrom (70).
World No. 1 Lydia Ko of New Zealand, trying to maintain her 82-week run atop the rankings, stumbled to a 73 and finished in a four-way tie for 10th in a grouping that included second-ranked South Korean Ryu So-yeon (68).
(Compiled by Peter Rutherford)
Share
