With his second victory on the region's premier Tour this season, the Thai veteran also completed his royal collection having won the Queen's Cup twice in 2012 and 2014 when it was staged as an Asian Tour event.
Lahiri, who led from the opening day, had to settle for a share of second place with Australia's Andrew Dodt while Qualifying School graduate Kalem Richardson of Australia enjoyed another good outing in Thailand by taking a share of fourth place with Thailand's Donthai Boonma and Paul Paterson of the United States.
Arjun Atwal (75) was tied 54th at three-under 285 while S Chikka (72) recovered form his third round 78, to finish at one-under and in tied 63rd place.
Lahiri was visibly disappointed not to have won again as another victory at the US$500,000 event would have meant more world ranking points and allowed him to close the gap on Order of Merit leader David Lipsky of the United States.
"I would have like to have won this week. We are not playing for lots of money and it's difficult to bridge such a big gap and I'm running out of tournaments. I've to win at least one of these next three events to have a chance at winning the Order of Merit. I'm a little upset I didn't close it out as I led wire-to-wire this week. I guess Thaworn was the better player today. I don't think I played poorly but it was just not good enough to close it out," said Lahiri.