- World No.1 delighted by 'miracle' win
- New Zealander posted final round 69
- Putt on 17th proved key to victory
World No. 1 Ko, 18, wrapped up what she called a "miracle" at Mission Hills Country Club, having been two shots behind with just two holes left to play.
The New Zealander posted a final round 69 to finish on 12 under par, one shot clear of England's Charley Hull and Chun In-gee of South Korea.
And she and her entourage celebrated by braving a leap into Poppies Pond, the lake by the 18th green.
Her nerveless finale was tough to take for Thailand's Ariya Jutanugarn, who had seemed on course for victory with three holes to go but bogeyed them and ended up on 10 under.
"It's amazing," Ko told LPGA.com
. "I've never really played well at this course before -- so to know that I can play well at a course I haven't really played well before gives me confidence."
She sunk a crucial par putt on the 17th to give her the chance of grabbing victory and said: "Something like a miracle needed to happen, so I think 17 was probably the most crucial putt."
But reminded that she had become the youngest two-time winner of the LPGA era, Ko indicated that she believed age was just a number.
"Just to embrace this win, I think that's the special part -- more than being the youngest something," she added.