Pak, the lone player under par for the tournament, finished six shots clear of Sweden's Carin Koch to collect the top prize of $225,000.
The triumph came on the heels of her victory two weeks ago at the Tournament of Champions in Alabama.
Battling winds of up to 35 miles per hour and temperatures in the 40's on Sunday, the 25-year-old Pak compensated for her bogeys on holes No. 2, 11 and 14 with birdies on No. 9, 12 and 15.
"From my practice time this morning, I knew it was going to be very difficult today," said Pak, who won her fifth title of the year. "My practice shots, they were flying 50 yards away from what I expected, and it was very cold as well. But obviously, now that I've won, it was easy."
Pak profited during the calmer first-round conditions on Friday. She carded a 65 to take a four-shot lead and, as the weather worsened, her position atop the leaderboard gradually became
"There was a lot of pressure. There is always a lot of pressure coming back to Korea to play golf," Pak said. "Because it's an official LPGA tournament, it was different than other times I've played events here, but I think I controlled myself well. I kind of just freed my mind, and it feels really great to win this tournament for Korea."
The Daejeon native won her 18th career title on the LPGA Tour.
Also having to contend with being three months pregnant, Koch holed a four-foot birdie putt on 18 to secure sole possession of second place and $139,638.
Her final-round 73 consisted of five birdies, four bogeys and a double-bogey at 11.
Koch also finished second to Pak at the Tournament of Champions.
Scotland's Mhairi McKay also birdied 18, finishing the tournament 4-over-par and in a third-place tie with Canada's Lorie Kane.
Annika Sorenstam's attempt to tie the 1963 record of Mickey Wright with 13 wins in a season came to an end at Jeju Island.
The Swedish superstar, who has won nine titles this season with just three events remaining, finished with a 6-over-par 222 and in a tie for fifth with American Danielle Ammaccapane.
This tournament begins a three-week stay in Asia. It is followed by the World Ladies Match Play Championship in Narita, Japan, and Mizuno Classic in Otsu-Shi, Shiga, Japan.