EVIAN-LES-BAINS, France, July 29, 2012 (AFP) - The 24-year-old started the day tied with American Stacy Lewis, but had 11 single putts and eight birdies to post a 17 under par total and won by two shots from Lewis and Karrie Webb, the veteran Australian who won back in 2006.
Lewis, the leader from round one, eagled the last from 30 feet for a 68, while Webb birdied the final two holes for a 67.
China's Feng Shanshan, who holed a bunker shot for an eagle at the last and a 66, South Korean amateur Kim Hyo Joo (68), and the 2007 champion Natalie Gulbis (68) of the United States shared fourth place on 14 under par.
"This is so exciting," said Park, who dropped shots at the third and 11th but birdied four holes in each half. "Today I was red hot with the putter."
Park's win was just her second as a professional, but she has proved she has the nerve for the big occasion.
Her first win was as a 19-year-old in the US Women's Open - and the 350,000 euro ($431,000) first prize at Evian is the most lucrative in women's golf.
"It's been tough to wait so long for another win but I think this will be really big for me."
By contrast her playing partner Lewis, the runner-up last year, could not buy a putt in the first 14 holes and had another hiccup when she cracked the face of her driver hitting from the 12th tee.
But she battled bravely with birdies at the 15th and 16th and then holed the monster for eagle at the 18th.
South Korea's 17-year-old amateur Joo completed an amazing week with her 68 - her fourth sub-70 score - for 14 under par.
Winner of the World Junior (15-17-years) Championship last year, Kim has already won as a 16-year-old amateur on the Korean and Japanese Women's Tours and intends joining the professional ranks at the LPGA Championship in South Korea in October.
"I have had a great time here," she said through an interpreter. "It was really good fun and I played really well."
Karine Icher, who has had three top tens on the LPGA Tour in America this season, was on her first trip back home to France since the birth of her first child, Lola. And she produced a great final round of 69 to tie for 12th place on nine under par.
Lola is 11 months old, and the 33-year-old said: "My life has changed forever since she arrived. To have a baby, it's completely different. Now my priority is not my golf but my daughter. But I'm more relaxed and it's fun to travel with her."
Icher had four birdies in the final round and she is already looking forward to next year when the tournament will become the fifth women's major alongside the US and British Women's Opens and the Kraft Nabisco and LPGA Championships.
"It's going to be super," she said after her closing four birdie round.
"France is not a big country. We don't have a lot of golf courses like in the United States. We're going to have the Ryder Cup in 2018 and next year we're going to have a women's major. It means so much."
Leading final round scores at the Evian Masters USLPGA and LET tournament here on Sunday (par 72, * denotes amateur).
271 - Park Inbee (KOR) 71 64 70 66
273 - Karrie Webb (AUS) 70 69 67 67, Stacy Lewis (USA) 63 69 73 68
274 - Feng Shanshan (CHN) 68 72 68 66, Kim Hyo Joo (KOR) 69 68 69 68*, Natalie Gulbis (USA) 69 69 68 68
276 - Anna Nordqvist (SWE) 72 67 69 68
277 - Pak Se Ri (KOR) 70 69 69 69
278 - Beatriz Recari (ESP) 71 66 75 66, Hee Il Hee (KOR) 66 67 76 69, Paula Creamer (USA) 68 67 73
279 - Giulia Sergas (ITA) 71 72 69 67, Momoko Ueda (JPN) 69 72 69 69, Karine Icher (FRA) 70 72 68 69, Cristie Kerr (USA) 71 69 67 72
280 - Azahara Munoz (ESP) 70 68 72, Lee Meena (KOR) 69 69 72 70, Mika Miyazato (JPN) 67 69 73 71, Lindsay Wright (AUS) 71 70 68, Lee-Anne Pace (RSA) 69 71 68 72
281 - Ai Myazato (JPN) 71 70 70 70, Julieta Granada (PAR) 74 65 71 71, Park Young Hee (KOR) 65 72 71 73
282 - Brittany Lang (USA) 71 69 74 68, Yang Amy (KOR) 72 68 73 69, Kim In Kyung (KOR) 69 73 71 69, Seo Hee-Kyung (KOR) 71 69 71 71, Lee Mirim (KOR) 73 68 70 71, Suzann Pettersen (NOR) 69 71 68 74, Carlota Ciganda (ESP) 73 69 66 74
283 - Choi Chella (KOR) 73 68 72 70, Ryu So Yeon (KOR) 73 65 72 73, Shin Jiyai (KOR) 69 69 71 74