She kept her nerve on the final hole of yesterday's tournament at the Highland Meadows Golf Club as she made birdie at the par-five 18th to move to 15-under as she took a one-shot lead to the clubhouse.
The teenager then tried to find a viewing spot as Korean So Yeon Ryo had a birdie putt of her own on the last but couldn't drain it as she finished in second place at 14-under.
"I actually couldn't see it properly because I was behind some people," Ko said. "Yeah, I kind of saw by the crowd's reaction."
Ko's final round of 65 included six birdies and no bogeys, which helped her chip away at the two-shot deficit she faced when she began the day in fifth place. The result took her to third on the LPGA Tour's money list for the year, while she is also in the same spot on the Race to the CME Globe standings, which is the season-long points race for the tour.
The US$210,000 ($241,411) winner's cheque boosted her earnings on the LPGA Tour this year to US$1,061,019. At 17 years, two months and 26 days, she became the youngest player to break the million-dollar barrier, eclipsing the previous record held by American Lexi Thompson.
"Pretty sure that goes into my mum's account or something," Ko said of the money. "But, yeah, I don't really think about money when I'm out here. When they give you the cheque I go, 'Oh, it's $210,000.' That's big money, but when I'm out there I'm thinking about making birdies and hitting good shots and making putts rather than, okay, this putt is going to give me an extra thousand."
Given her undoubted potential, religious practice regime and cool demeanour, there's little reason to doubt that she will only improve in the coming years.
The Florida-based professional will now take a couple of weeks off before the Meijer LPGA Classic in Grand Rapids, Michigan on August 7.
