"It means so much," a tearful Masson told Golf Channel after being doused with beer by several of her peers, including runner-up Minjee Lee.
Masson finished at 16-under 272 for her first LPGA victory, with Australian Lee (68), South Korean Lee Mi-hyang (71) and France's Karine Icher (66) equal second on 15-under.
An anticipated showdown between world number two Ariya Jutanugarn and number one Lydia Ko never materialised, though both were in contention until late.
Thai Ariya, seeking her sixth victory since May, missed a three-foot putt at the 15th and later hooked her tee shot into an unplayable lie in thick woods at the last and had to retee.
She finished two strokes off the pace, equal fifth with New Zealander Ko and Norway's Suzann Pettersen.
Masson's victory was just the second of the year by a European in a season dominated by Asian-born players.
"I’ve been out here for a long time. Four years is a long time," said Masson, 27, who clinched victory with a tap-in par at the last. "I’ve just gotten better every year, working hard."
She said that dropping two shots at the first hole and falling five strokes from the lead perhaps helped her relax.
"It's hard to believe I came back after that start. Maybe the pressure was off a little bit.
"It’s a golf course where you can make a lot of birdies and that’s what I tried to do. It was super-important to birdie the second hole and just get it going and see some putts go in."
(Reporting by Andrew Both in Cary, North Carolina; Editing by Ken Ferris)
