The former world number one also snapped a three-year winless streak by lifting her 11th LPGA Tour title with her winning four-day total of 22-under-par 266 at the Siam Country Club.
Atthaya Thitkul, who had the chance to force a play-off with a birdie at the last hole, could only manage to close with a par when play resumed, having been suspended for more than an hour due to inclement weather.
Ariya started her final round five shots off the lead in ninth place but fired an ominous warning to her rivals by charging out with three successive birdies starting from the first hole.
After making pars on holes four and five, the two-time major champion stormed towards the turn with three birdies in her next four holes.
She continued her birdie blitz on 10 and 12 and remained steady with another five straight pars from the 13th hole before a closing birdie on 18 sealed an emotional victory for the 25-year-old.
“This victory means a lot to me because I have always wanted to win in Thailand and I finally did it.
“I had a tough time the last two years. Sometimes, I tell myself I want to rest and stop (playing golf) for a while. But at the same time, I know I cannot give up as I need to try harder and one day, that win will come again,” said Ariya.
Despite coming so close to her breakthrough on the LPGA Tour, Atthaya was delighted with her sterling performance on home soil.
“This is like a new experience for me, having come so close to a win. But I’m already feeling very proud to be here and it’s always amazing to be playing at home,” said Atthaya.