His four-day, 16-under-par total of 272 was enough to leapfrog previous leaders Gavin Green and Phachara Khongwatmai and hand him a one-shot victory yesterday at the sun-baked Tanah Merah Country Club.
The Singapore tournament was part of the new International Series, which received funding of US$400 million (B14.1 billion)from the Saudi-backed LIV.
The final day of the event was set for a dramatic showdown, with 11 players within three shots of the lead going into the back nine.
However, it was Nitithorn who eventually reigned supreme, crediting his mental game for helping him win his biggest career title to date.
“I’m really (at a) loss for words with this victory. It’s my biggest win so far and I cannot describe my feeling. I was fully focused on the process and playing my own game the entire week,” he said.
“I kept believing in myself and did not allow myself to be distracted by other pressures. I’m so happy I managed to win this week.”
Malaysia’s Green, who had led the tournament since the second round, could have forced a playoff with Nitithorn had his birdie putt from 15 feet dropped into the hole at the last.
Green instead settled for a share of second place with overnight co-leader Phachara, of Thailand, and Canada’s Richard T Lee, all of whom signed off with identical 273s.
“I don’t think the last putt could have gone any closer to the hole. I thought I had made it. But it stopped breaking right at the end. But it is what it is. This is golf. I gave it a chance and that was all I could do,” said Green.
Australia’s Todd Sinnott shot the day’s lowest score of 64 to finish in a tie for fifth with Taiwan’s Chan Shih-chang.
Chan looked to be heading for a grandstand finish after snatching the outright lead on 16-under with a birdie on 14. However, a disastrous triple bogey on 18 dashed all hopes of securing his fifth win on the Asian Tour.
LIV Golf rebel Patrick Reed, meanwhile, could not live up to his pre-tournament billing, blaming his putting woes for a tied 31st place finish, eight strokes behind Nitithorn.
“It was a frustrating week, golf-wise. Just one of those weeks when the putter was not working,” said the American, who posted rounds of 73, 68, 72 and 67.