'I am happier than I imagined,' said Park, who shot a 65. 'This is my first tournament win in Korea.'
Annika Sorenstam and fellow Swede Carin Koch shared second place at 11-under- par 205 after they each posted final round 67s. Shi Hyun Ahn, the 2003 champion, closed with a 3-under 69. She was joined in fourth place at minus-10 by Jeong Jang (68) and Lorena Ochoa (67).
Park held a share of the lead after each of the first two rounds. After round one, she was tied with Koch and after round two she shared first with Kate Golden. Park fell out of the lead quickly in the final round as she bogeyed the first.
The Seoul, South Korea native atoned for that error with a birdie at the par-5 third. Park converted a birdie try at the sixth to move to minus-10, which put her two strokes clear of the field at Nine Bridges Golf Club.
Park caught fire around the turn. She drained a birdie putt at the ninth and came right back to birdie No. 10 and move four shots ahead of the field.
The six-time winner made it three straight as she birdied the 11th to get to 13-under. Park parred her next three holes before she birdied the 15th.
Park closed the tournament in style. She birdied the 17th and came right back to birdie the par-5 closing hole for the third time in the tournament.
'Today, my plan was to do my best on every single shot,' Park said. 'I tried to think positively.'
Sorenstam, the women's world No. 1, made a run at the lead in the final round but came up short. She drained back-to-back birdies from the fifth and added a birdie at the par-5 ninth to get within one shot of Park.
However, Sorenstam tripped to a bogey at the 11th. She came back with consecutive birdies from the 14th, but faltered to another bogey at the 17th. The 34-year-old closed with an eagle at the last to share second place.
Koch opened with a birdie at the first, but stumbled to her lone bogey at the third. The 33-year-old picked up birdies at the fifth and seventh to move to minus-8.
Koch, a three-time Solheim Cup performer, continued her steady climb up the leaderboard with birdies at the 12th and 14th. She managed to join Sorenstam in second place with a birdie at the par-3 17th.
Young Kim and Jill McGill shared seventh place at 9-under-par 207. Golden stumbled to a final-round 73. She ended at minus-8 alongside Soo-Yun Kang.
Korean Se Ri Pak finished at 7-under-par 209. She was joined there by Americans Stacy Prammanasudh and Sherri Steinhauer, as well as Europeans Catriona Matthew and Women's British Open champion Karen Stupples.