'My knees, my arms, my whole body was shaking,' said Park, who finished at 11- under-par 277. 'I don't know if anybody else is that way, but I remember every win that I've had, seriously, I didn't know if I could start the club.'
Park stood on the 18th tee with a two-shot edge over LPGA Tour rookie Aree Song. Song, who was trying to become the youngest player to ever win a major on the LPGA Tour, roped her approach onto the green and watched as her ball rolled inside 30 feet of the cup.
Park played her second shot short of the water and knocked her third to 6 feet before Song drained her eagle putt to take the clubhouse lead at 10 under par.
'I knew I had to make a three to have any chance,' said Song. 'I just read it perfectly.'
There was plenty of excitement left however. Park, who fell short of her first major win in a playoff to Annika Sorenstam at last year's LPGA Championship, responded and calmly converted the birdie try for the biggest win of her career.
'I knew exactly what I had to do,' said Park, who won for the fifth time on the LPGA Tour. 'I watched Aree's putt, actually. I saw it go in the hole and then I knew that I really, really had to make my 6-footer.'
Park, who began the day tied with Song at 8 under, found trouble early with a bogey at the third.
The turning point came around the turn for Park with a birdie at the ninth. She added a birdie at the 10th and another at the 11th to grab the outright lead.
At the par-4 12th, Park dropped her second shot within 6 feet of the cup and sank the putt for her fourth consecutive birdie to open a two-shot edge over the field.
The 25-year-old struggled off the tee en route to a bogey at the 15th but showed her experience with a perfect play at the last to take home the title on the Dinah Shore Course at Mission Hills.
'It's believing in myself,' said Park. 'Believing in my hard work that I had done. Just trusting that I could do this, If you want it really, really badly, you can get it. And I guess I was the one that wanted it the most.'
Song grabbed the lead with a birdie at the second and pulled two ahead with a birdie at the 10th.
The 17-year-old faltered with a bogey at the very next hole, however, and fell further back with a bogey at the 16th.
Song persisted and finished the best way she could with an eagle at the last to secure second place alone at 10-under-par 278.
'I just don't think I could have done anymore,' said Song, who shot a 70. 'I felt like I squeezed out a lot of shots today with the game I had. When you don't hit it in the fairway here it's a very difficult course to make birdie on.'
Karrie Webb birdied the 18th to complete a round of 69. She finished alone in third place at 9-under-par 279, one shot clear of another young star.
Michelle Wie was impressive again on Sunday as the 14-year-old carded a 1-under 71 to finish fourth at 7-under-par 281.
Wie, who tallied two birdies and a bogey in the final round, improved her result from last year's tournament for her best career finish on the LPGA Tour.
'I kind of feel drained right now. I'm just so tired. It's just been four long, hot days,' said Wie. 'I was tired today but I made a promise to myself today even if nothing works out that I'm still going to fight until the end.'
Cristie Kerr posted a 69 to join Catriona Matthew in a tie for fifth at 6-under-par 282. Mi Hyun Kim was one shot further back at 5-under-par 283.
Rosie Jones, Lorena Ochoa, Candie Kung, Christina Kim and Jung Yeon Lee shared eighth place at 4-under-par 284.
Annika Sorenstam, whose bid for a single season grand slam will have to wait until next year, closed with a 69 to finish one shot further back at 3-under-par 285 along Hee-Won Han and Stacy Prammanasudh.