The fog-delayed OneAsia tournament was completed on Monday, with Kim finishing at two under at Woo Jeong Hills Country Club.
Kim made par on his final five holes as he clinched his second OneAsia title of the season.
Noh Seung-yul (69) was second at even par as South Koreans dominated the leaderboard.
Lee Tae-hee (69), Choi Ho-sung (72) and amateur Ham Jeong-woo (75) were tied for third at one over.
Ham held a two-shot lead after the third round but had a forgettable fourth, including a double bogey at the par-four 12th.
South Korean YE Yang, the 2009 PGA Championship winner, was outright sixth at two over.