Choi, who first won the event two years ago, finished the final round in style by sinking a 16-foot birdie putt on the 18th hole at the Il Dong Lake Golf Club for a total score of 13-under 275.
The local hero made five birdies in the final round, including two in a row on the 11th and 12th holes, but double-bogeyed the par-4 14th.
'I think I played well because of so many fans,' said Choi, who hugged his son and daughter following his win. 'This win is very meaningful to me.'
Andrew Buckle of Australia, who entered the final round as Choi's co-leader, shot a 2-over 74 to share second place with U.S. Masters winner Fred Couples (69) at 8-under 280.
Couples appeared to be catching Choi after firing five birdies, but conceded a bogey on the last par-3 hole to remained in second place.
Thailand's Thaworn Wiratchant shot a final-round 72 for a 281 total and fourth place.
The U.S. $500,000 SK Telecom Open is the 11th leg of this season's Asian tour.
Copyright 2005 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.