Back-to-back rounds of 67 on Saturday and Sunday allowed the 23-year-old to improve from seven shots off the 36-hole pace set by Shanshan Feng to win by two over 17-year-old amateur Hye-Jin Choi.
Park fired off her second consecutive five-under round to finish at 11 under for the event and earn a two-stroke win over Hye-jin Choi, the amateur who entered the day with a share of the lead.
Lee's finish is the latest in a solid season for the three-time LPGA Tour victor, who has six top-10s in 2017, and remains confident her first major victory is near. But her downfall came on the par-3 16th, when her tee shot from 145 yards flared off short and right into the water.
In her US Women's Open debut past year, Park led by two shots after 36 holes but closed with back-to-back 74s and settled for a share of third.
"I did pretty well until the last hole", Feng said, per Ron Sirak of the LPGA's official website.
EUROPEAN TOUR: Rafa Cabrera Bello birdied the first hole of a playoff with Callum Shinkwin to win the Scottish Open, securing his first title in 51/2 years. "Of course, I did have many winnings in other tournaments, but winning here at U.S. Open means so much more, and for that I am grateful and extremely happy".
CHAMPIONS: Scott McCarron shot bogey-free 6-under 66 and took advantage of a collapse by three-time defending champ Bernhard Langer to win the Senior Players Championship in Owings Mills, Md.
Park hit six birdies and one bogey in the fourth and final round to card an 11-under 277.
She stretched clear of the field on the back nine thanks to birdies at the 12th, 15th and 17th and then held her nerve at the 18th with a superb up and down from the back of the green to salvage par. "I'll keep trying. I'm going to do the same things and see what happens", she said.
From there, she chipped to within three feet and made the putt to save par. "So fans gave me that nickname a year ago that I just focus on attack and aggressiveness".
Michelle Wie and Brittany Lang were tied for the last two automatic spots and earned no points at the U.S. Women's Open.
Feng was frustrated by her putting until the par-five last hole.
"The first two days didn't go as well as I thought they would", said Park, a South Korea resident, through an interpreter. She rallied with a birdie on the par-5 18th to finish solo second. Choi birdied the final hole, but when all the pars and bogeys and whispers and shouts of "Donald Trump!" were added up, Park's four-round score was lower than everybody else's. "So, to me, getting this second place runner-up actually means more and it's a great honour for me so I am not really focusing on the prize money for now". "He's a great competitor, and I was kind of shocked he bogeyed 17", said DeChambeau, the 10th first-time victor on the tour this season. She is now in third place with 95 points, with fellow South Korean Ryu So-yeon leading the way at 150 points, followed by Lexi Thompson with 105 points.
"My last three U.S. Opens, I think I missed two cuts and last year I just made the cut so actually this year is such an improvement".