BANGKOK, December 15, 2013 (AFP) - Looking relaxed, the Spaniard fired a four-under 68 on the final day of the $1 million Asian Tour event, giving him a dazzling 22-under par finish of 266 for the tournament.
It was his 21st career victory and his fourth Asian Tour title.
Starting the day four shots behind, runner-up Henrik Stenson came within two shots of Garcia mid-way through the round. But that was as close as it got for the Swedish star, who matched Garcia's 68 for the round to end on an overall 270.
France's Alexander Levy clinched third place with a final-round 69, to end four strokes behind Stenson at the Amata Spring Country Club.
Defending champion Charl Schwartzel was among a quartet of players who shared fourth place. He hit his second consecutive 67, but was unable to recreate his 2012 masterclass.
Joining the South African on a tournament 275 were England's Justin Rose who also could not dent Garcia's lead, Yuki Kono of Japan and India's Anirban Lahiri.
Chapchai Nirat was Thailand's best finisher in joint eighth place with America's Rickie Fowler.
"It was great to win in my last tournament of the year," said Garcia, who sank six birdies and dropped two shots in his final round.
The win is expected to move him up into a top-10 world ranking.
With the in-form Stenson his main challenger on the final day, Garcia said he knew he could not afford too many slip-ups.
"Henrik has been playing so well lately, I could not afford to slip up," Garcia said, admitting he stuttered briefly on the last three holes of the front nine before recovering with a hat-trick of quick birdies on the back leg.
With just two holes to go he knew all he had to do was keep the ball out of the water to ensure victory.
"I hope I can carry this form into next season," he said.
The Spaniard said his girlfriend, who was his caddie for the event, played a big part in his success, but he confirmed he would return to his regular caddie next season.
Runner-up Stenson praised Garcia's performance.
"Sergio just played so well," he said. "Being four shots back I needed something really good to happen, but I missed a couple of good birdie opportunities."
The Swede said that when Garcia notched three straight birdies on the back nine he knew it was "done and dusted".
US Open Champion Justin Rose said he struggled to recover from a bad start.
While he failed to win in Thailand, Rose said he had enjoyed the "fun tournament" in the Thai sun.
"But I will be happy to put down my clubs for a few weeks. I've had an amazing year."
Scores after the final round of the $1 million Thailand Golf Championship on Sunday at the Amata Spring Country Club (par 72).
266 - 68-65-65-68 Sergio Garcia (ESP)
270 - 70-67-65-68 Henrik Stenson (SWE)
274 - 70-65-70-69 Alexander Levy (FRA)
275 - 68-73-67-67 Charl Schwartzel (SAF), 72-69-65-69 Yuki Kono (JPN), 65-68-70-72 Justin Rose (ENG), 71-64-67-73 Anibarn Lahiri (IND)
277 - 72-69-67-69 Chapchai Nirat (THA), 70-66-71-70 Rickie Fowler (USA)
278 - 71-71-68-68 Thongchai Jaidee (THA), 69-73-67-69 Marcus Fraser (AUS), Gaganjeet Bhullar 66-73-69-70 (IND)
279 - 71-72-68-68 Hunter Mahan (USA), 74-68-65-72 Chinnarat Phadungsil (THA)
280 - 72-71-68-69 Baek Seuk-hyun (KOR), 74-68-68-70 Ryo Ishikawa (JPN), 72-71-66-71 Berry Henson (USA)
281 - 72-72-71-66 Prayad Marksaeng (THA), 69-70-72-70 Masahiro Kawamura (JPN), 75-68-67-71 Masanori Kobayashi, 64-71-73-73 Alec Cejka (GER), 69-68-71-73 Kiradech Aphibarnrat (THA), 73-69-66-73 D.A. Points (USA), 71-68-67-74 Panuphol Pittayarat (THA), 74-68-64-75 Kim Gi-whan (KOR)
Selected scores
283 - 70-70-71-72 Bubba Watson (USA)
286 - 73-70-73-70 John Daly (USA)