BANGKOK, 15 Feb 2015 (AFP) - Five birdies in a flawless final-round 67 left him 16 under for the tournament, with 272 over the four days' competition at the Black Mountain course in Hua Hin.
It was enough to edge him ahead of Thai star Thongchai, who was well set until a horrible double-bogey on 13 left him playing catch up for the co-sanctioned European and Asian Tour title.
Thongchai finished with 71 for the day and 273 overall, level with third-round leader Scott Hend -- who was left to rue bogeys on seven, fourteen and seventeen to go round in 72.
Dodt has been in dismal form since winning the Avantha Masters in India in 2010. He lost his European Tour card in 2013 and had to endure qualifying school last November.
"I'm speechless -- it's just come out of nowhere," the stunned 29-year-old said, according to a European Tour release.
"I played really well yesterday and today but I just didn't think I'd come out on top," he added.
"To be honest, losing my card 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."
Round of the day went to Canada's Richard T. Lee who hit six birdies in a perfect 66 to drag himself into a top ten finish. His 14 under put him level with America's Jason Knutzon and another local favourite Kiradech Aphibarnrat.
Early pace-setter Miguel Angel Jimenez endured a poor day, finishing one over after blundering through the front nine. He drifted to 13 under for the tournament three shots off the lead, alongside Spanish compatriot Carlos Pigem, Sweden's Johan Carlsson and Wade Ormsby of Australia.
Leading scores after the final round of the $2 million Thailand Classic at the Black Mountain Golf Club in Hua Hin on Sunday:
272 - Andrew Dodt (AUS) 71-67-67-67
273 - Thongchai Jaidee (THA) 69-66-67-71, Scott Hend (AUS) 67-68-66-72
274 - Richard T Lee (CAN) 68-67-73-66, Jason Knutzon (USA) 72-66-69-67, Kiradech Aphibarnrat (THA) 67-67-70-70
275 - Carlos Pigem (ESP) 65-72-72-66, Johan Carlsson (SWE) 69-67-70-69, Wade Ormsby (AUS) 72-65-68-70, Miguel Angel Jimenez (ESP) 67-66-69-73,
276 - John Parry (ENG) 71-69-70-66, Sam Brazel (AUS) 69-69-71-67, Shiv Kapur (IND) 66-73-69-68, Alex Noren (SWE) 67-70-68-71
277 - Anthony Wall (ENG) 72-68-70-67, Jeunghun Wang (KOR) 68-69-71-69, Jorge Campillo (ESP) 73-68-66-70, Jyoti Randhawa (IND) 71-70-65-71, Javier Colomo (ESP) 74-67-65-71, Richard Green (AUS) 71-67-67-72