At 20 years old, Henderson is now two victories behind Sandra Post for the most ever by a Canadian on the LPGA tour.
Playing the final round two shots behind the leader, Brooke Henderson of Canada, Park played an unusually inconsistent round.
With bogeys on holes two, nine and 12, Ko wasn't making headway, but she picked up her game late, adding to her birdie on hole three with three successive ones from 14 to 16, before also going under on 18.
With four birdies and one bogey in the final round, Henderson shot a 3-under 69 to finish 12-under par for the tournament, giving her a four-stroke victory over Azahara Munoz of Spain. Henderson and sixth-ranked Ariya Jutanugarn (69) were the only other golfers to break 70 on a day that featured rain squalls and winds gusting to 30 miles per hour.
Pernilla Lindberg shot 70 in her first start since beating Park in an eight-hole playoff in the year's first major.
"The wind wasn't as strong early today and there were softer conditions", said Henderson.
Ji Eun-hee was the second-best finisher among Korean golfers at the Lotte Championships, finishing tied for 11th at 3 under par along with KLPGA Tour golfer Kim Ji-hyun who played under invitation.
HILTON HEAD ISLAND, S.C. (AP) - The resurgent Ian Poulter shot a 4-under 67 on Saturday to take a one-shot lead into the final round of the RBC Heritage, putting him in position for his second victory in three weeks. In Hilton Head (United States), Rory Sabbatini battled through the discomfort of a sore back to shoot a seven-under 64 for first-round lead at the RBC Heritage, with world number one Dustin Johnson not far behind.
Second-round leader Bryson DeChambeau had the confident stride of a pending victor with his first solo 36-hole lead as a pro - at least until the third round got going.
DeChambeau had been 6-under par on Harbour Town's three par 5s the first two rounds.