Michael Hoey finished eight shots behind winner Andrew Dodt at the True Thailand Classic.
Hoey carded a final round 71 on Sunday to end up in a tie for 31st position on eight under.
The Northern Irishman fired a course record 64 on the opening day before rounds of 72 and 73 on Friday and Saturday.
Australian Dodt fired a closing 67 to end 16 under, one ahead of compatriot Scott Hend, who led on 15 under going into the final round, and Thongchai Jaidee.
Word number 281 Dodt carded five birdies and no bogeys in his final round at the Black Mountain Golf Club to win his second European Tour title after success at the Avantha Masters five years ago.
If Dodt was nervous when he began his final round, he was not showing it and any butterflies soon evaporated as he birdied the first three holes to make the best possible start.
He parred his next six holes to finish the front nine three under, and picked up further shots at the 12th and 15th while he did not drop a shot to collect his second European Tour victory five years after his first.
Jaidee had a less straightforward round and found himself almost out of the reckoning when he dropped two shots at the par-five 13th hole.
He responded by registering successive birdies at the 14th and 15th but dropped another shot at the 16th to fall one behind the leader.
A par at the 17th meant Jaidee needed a birdie at the 18th to force a play-off but victory was Dodt’s when the home favourite could only make par.
“I’m speechless - it’s just come out of nowhere,” Dodt told the European Tour website.
“I played really well yesterday and today but I just didn’t think I’d come out on top. I knew I was playing well but to come out and win is just a dream come true.
“To be honest, losing my card two years ago was probably the best thing that could have happened to me.
“I went home last year, spent 12 months at home, played the Asian Tour again, found myself again, found my game and to be in the winner’s circle again - it’s unbelievable.”
Ireland’s Damiem McGrane posted a final-round 70 to take joint 66th place on three under.