Kim finished with a seven-under 65 final round to close at 31-under for the tournament, four shots better than the record she previously shared with Annika Sorenstam.
Speaking of her 63-65-64-65 tournament, surpassing Annika Sorenstam's 27-under record from 2001, she told LPGA.com: "After I shot 27-under (at the 2016 JJTBC Founders Cup), I wanted the 72-hole record".
Ko had three bogeys and two birdies, all on her front nine, and played par golf after the turn to slip down the leaderboard.
The only blemish on her scorecard came on Friday with a double bogey on the 17th hole.
"Just before starting (Sunday), I was just setting my goal as a bogey-free round", Kim said. No one, and I mean no one ever dreamed there would be this many birdies but the Oneida Nation is a generous bunch and there was nothing wrong with witnessing golf history this week, re-written by one Sei Young Kim.
The result never looked in doubt as Kim began Sunday's round with an eight-shot lead, and it proved to be the case as she tore up the course for the fourth successive round. She was streets ahead of the field as she won by nine shots with Carlota Ciganda in second spot at 22-under while Anna Nordqvist, Emma Talley and Amy Yang were tied for third at 20-under.
"It's unbelievable the way she's playing", Ciganda said of Kim.
Those getting the chance to watch Kim and Yang in tomorrow's final round either live or via the television coverage should take note of two of the best swings on the LPGA Tour. During the final round, Kim showed outstanding accuracy with her iron shots, with a Greens in Regulation percentage of 94.4.
It was also the seventh win by a South Korean during this season's LPGA Tour. "Even if I break (the record), I'll keep (making) the challenges higher. When someone plays that good, she deserves to win". That victory had propelled her to eighth in the world, although she had slipped to 26th coming into this week.
During her first season on the LPGA Tour, Kim won three tournaments to earn the Tour's Rookie of the Year award.
She was ranked as high as number eight in the world a year ago after her win in Mexico and has struggled for much of 2018.
England's Bronte Law finished alone in 6th at -18 which included a birdie on the 18th.