World No 1 Jeeno Thitikul justified her top billing in emphatic fashion after edging Japan's Chizzy Iwai by one stroke to claim her home LPGA Thailand tournament for the first time.
The Thai star kept her composure under sweltering conditions and intense pressure to card a closing four-under-par 68, finishing on 24 under.
The victory marked her eighth LPGA Tour title and her first triumph on home soil.
England's Lottie Woad finished tied-15th on 15 under.
"I would rate it A triple-plus," said the 23-year-old Thitikul. "I know it's not as big as the majors, but winning in my home country means so much to me - sometimes even more than a major."
Thitikul became the third Thai winner of the tournament, following Ariya Jutanugarn in 2021 and Patty Tavatanakit in 2024.
The win was made even more special with her mother watching in person after the Thai had made eight previous attempts at the event.
"My mom came up to me after I finished 18 and she cried a lot," Thitikul said. "I told her, 'I finally won in front of you'. She was emotional, and that made me emotional too."
World No 19 Iwai mounted a strong challenge, drawing level briefly after rolling in her second eagle of the day on the par-five 10th.
However, the Japanese added no further birdies and signed for a 66 to finish runner-up on 23-under-par 265. Korea's Hyo Joo Kim, the world No 9, posted a 68 to take third at 22 under, while compatriot Lee Somi, the opening-round leader, finished fourth on 21 under.
Former world No 1 Lydia Ko carded a 68 to tie for fifth alongside Denmark's Nanna Koerstz Madsen, who produced the lowest round of the day with a scintillating 63 as both ended the week on 20 under.
Defending champion Angel Yin shot 70 and was in a tie for 48th at five-under 283.
The tournament about 125km (75 miles) east of Bangkok was the first of three events in Asia in consecutive weeks, to be followed by those in Singapore and China in the early Asian swing on the LPGA Tour.
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