Ko carded an excellent final round seven-under 65 to finish at 11-under for the tournament, a remarkable six shots behind runaway winner Eun-Hee Ji.
Ji finished what was a dominant four days of golf by also shooting 65, for her third win on the LPGA Tour, and first since 2009.
Ko, in a winless stretch of her own, finished strongly for another second place finish, after also claiming a runner-up last month in Indianapolis.
This week's result is her fifth straight top 25 finish, and she will be left ruing a second round 74, which meant her fantastic weekend finish was never going to contend with the efforts of Yi.
Ko carded seven birdies with no bogies in her final round, finishing four shots clear of a share of golfers in third place, including world number one So Yeon Ryu.
