Lee, who is from Australia, took a three-shot lead into the final round over Harigae, having broken a 23-year-old record with her 54-hole score of 200 after shooting a 67 on Saturday.
The tournament took place at Pine Needles Golf Club in Southern Pines, North Carolina — the fourth time the venue has hosted the event.
The 26-year-old got her final round off to an ideal start with a comfortable birdie on the first hole, followed by another on the second as she drained a 30-foot putt.
Lee wobbled slightly on holes five and seven as she made bogeys, but recovered her composure to follow those errors with four pars and a birdie.
After 12 holes, the world’s fourth ranked golfer was six shots clear of the field and from there cruised towards the Harton S. Semple Trophy.
Lee’s younger brother and fellow professional golfer Min Woo Lee took to Twitter Sunday to congratulate his sister.
“This one hits hard. Tears in my eyes,” he tweeted. “So so proud. Just a kid from Perth. Two major wins to her name now.”