The Auckland native, winner of the Women's New South Wales Open on the Australian women's tour in January, closed with a five-under 67 to finish the tournament 13-under 275, three strokes better than South Korea's Inbee Park (69) who picked up 300,000 U.S. dollar as the top professional.

Ko became the first amateur to win on the LPGA Tour since 1969, and only the fifth player ever to achieve the feat. She is also the tour's youngest-ever winner, eclipsing Lexi Thompson who won the Navistar LPGA Classic last September as a 16-year-old.

Two weeks ago, Ko also won the prestigious U.S. Women's Amateur championship.

"Yeah, it's great to win, and the last few holes, it got a bit nerve wracking. But (playing partner) Stacy Lewis after my birdie on 15 she said, 'you know, you can do it,' and it was really great to have another player that I look up to giving me that much support. So it was really awesome."

Starting the day with a one-stroke lead on four players, Ko made the turn at one-under 34 and then proceeded to reel off four consecutive birdies starting at the 10th. She picked up another stroke at the 15th hole before a bogey-five at the last in front of a huge gallery of appreciative fans.

The teenager said her strategy for the final round was just to focus on her game, so much so that she didn't look at the scoreboard until the 17th hole.

"I kind of looked at it because I wanted to become more relaxed, and today I said I've got nothing to lose. I already got the leading amateur in my bag. And yeah, all I need to do is play my game, and my goal was four under, so I shot five under, which was even better," she said.

"I kind of tried to play the 18th quite relaxed, and everything went straight, but my adrenaline got to me and it went way past the green. And then I won. That's the most important part for me."

U.S. Women's Open winner Choi Na-yeon (68) finished equal third with her South Korean compatriots Chella Choi (71) and Shin Ji-yai (71), the two-time former China Women's Open champion, at five strokes off the pace. Sweden's Anna Nordqvist (69) and American Stacy Lewis (69) were a shot further back in the 2 million U.S. dollar tournament that served as a LPGA Tour major from 1969 to 1990.

World No. 1 Yani Tseng (74) finished equal 35th after earlier shooting a six-under 66 in the opening round, her best 18 holes of the summer. She then struggled through the final three rounds as she has done since early June.

"I just didn't drive well. I didn't putt as well like the first day, and everything else I just feel like it's about luck," she said. "You know, I just feel like I need a little bit more luck because I hit so many good shots, I hit so many good putts, it just didn't go in. But this is golf, it's not easy, but at least I'm enjoying it out there."

The Chinese Taipei star said she was impressed by what she had seen of amateur Ko.

"It's very impressed. Especially she's only 15-years-old. I didn't even know what I was doing when I was 15. So it's pretty amazing to see her play this good in the best stage. All the best golfers here and she's only like 15-years-old and trying to win a LPGA tournament," said Tseng, adding that the young players coming up were good for the game.

"Yeah, I feel I'm old on the tour now. I'm only 23, but there's so many younger players now."

World number three Feng Shanshan shot a one-under 71, her best round of the tournament, to finish at five-over to earn 5,837 U.S. dollars. Starting from the 10th hole, the Guangdong native was four-under through her first seven holes, before registering three bogeys on her back nine, the front nine, to finish equal 55th.

"I had a really good front nine (the back nine) ... I' ve never played it under par and I think it's a tough nine and you know I made three bogies (on the front nine). I still feel happy, you know, at least I shot one-under par this round."

Next year's Canadian Women's Open will be held in Edmonton, Alberta.