Even in a steady rain at Mountain Ridge on Sunday, the 26-year-old South Korean star made it look easy, closing with a five-under 66 for a four-shot victory over Caroline Masson, of Germany.

Ko started the final round with a four-shot lead and no one got closer than three all day as she wound up on 18-under 266.

Germany's Masson carded the low round of the day with a 64 while Elizabeth Szokol closed with a 69 to finish alone in third at 11-under par.

Jin Young Ko successfully defended her Founders Cup title in record style. PHOTO: Getty Images.

Jeongeun Lee6 (67) and US Women's Open champion Yuka Saso (70) tied for fourth.

Minjee Lee finished as top Australian, tied for 25th on four under after a final round 70, while compatriot Hannah Green (72) was two under, Su Oh (70, one under) and Katherine Kirk (70, even).

With the tournament as good as decided at the turn, it was a matter of how Ko would finish and she did so with four birdies in a five-hole stretch.

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It was her 14th consecutive round in the 60s, dating back to a 69 in the final round of the Evian Championship in July.

That ties the mark Sorenstam set in the middle of her 10-win season in 2005.

Sorenstam won three of four tournaments during that stretch of 14 straight rounds in the 60s, including a major, and was runner-up in another.

Ko has won twice and was runner-up and tied for sixth in the others during her streak.

Ko drives during the final round. PHOTO: Getty Images.

World No.2 Ko joined top ranked Nelly Korda as the only three-time winners on the LPGA Tour this season, and became the fifth South Korean with at least 10 victories - the record is 25 for Se Ri Pak.

Next up for Ko, who has played the last four weeks, is a trip home and a short break.

She plans to play the BMW Ladies Championship the following week in South Korea, the only Asian event on the LPGA Tour calendar because of the pandemic.

"I still have a chance (to) beat Annika – and I will try to do my best," Ko said after getting a champagne shower.

Ko successfully defended her title at the Founders Cup – which she won in Phoenix in 2019 – and pocketed $US450,000 ($A615,000) from the largest purse among regular LPGA Tour events.