The 22 year old's final round of 66 which included birdies at the final two holes would see the West Australian finish alone in second place behind winner, 19-year-old Nelly Korda.
For Lee, it is her 8th top five of the season and will move her into 2nd place on the 2018 money list behind only Ariya Jutanugarn with earnings of US$1,518,304.
“I'm pretty proud of myself today," said Lee. "I mean, the conditions were probably the toughest that we had all week, and yeah, my ball-striking was about today and my putting was good, as well. So pretty solid all around.
“Last year I had a goal and I didn't quite crack into it. So this year, I have. Yeah, I know I have a couple tournaments left but it's pretty cool to have achieved your goal and you can reset. It's a pretty good feeling.”
Lee’s round of 66 was the best of the day, the next best (67) recorded by American Ryan O’Toole who finished in 3rd place and one behind Lee.
Korda, a sister of former Australian Women’s Open Champion, Jessica, won her first LPGA Tour title after several near misses and it was an emotional moment for the American.
“Truthfully, I cannot put it into words. It still hasn't hit. It's definitely one of the best days of my entire life. I can finally check that off of my list, winning an LPGA event, something that I dreamed of ever since I started playing.
“I'm in shock right now, walking off the 18th, I saw my friends lined up and my sister was on FaceTime and I just lost it. I definitely had a couple tears going down my face.”
Of the other Australians other than Lee, Sarah Jane Smith was 26th, Hannah Green 48th and Su Oh and Katherine Kirk 60th.
SIGNATURE HOLES: 16TH AT CONCORD G.C. (NSW)
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