The Dubliner, whose last tournament success came at the 2008 US PGA Championship, started the day with a five-shot lead and victory was never in doubt as he closed with a three-under-par 69 at the Horizon Hills Golf and Country Club.
South Korean Noh Seung-yul finished strongly with a superb seven-under 65 to claim second place while Chinese Tapiei’s Lin Wen-tang took third following a 68.
Harrington had played through the pain barrier all day on Saturday after tweaking a muscle in his neck. He showed no ill effects from the injury and started with aplomb by reeling off three straight birdies from the second.
The 39-year-old bogeyed the fifth but added further gains on the 11th, 13th and 14th holes and though he dropped two shots in his last three holes it mattered not as he comfortably sealed victory on his debut at the Asian Tour event.
“Two years is a long time, especially when you’re reminded most weeks you play. It’s nice and very important for me to win. It’s somewhat a monkey off your back,” said Harrington.
“Winning is a habit. Every time you win, it is important but when you haven’t won for a while it does add a bit more emphasis to it.”
Fresh from helping Europe to Ryder Cup success earlier this month, Harrington had been in fine form throughout the tournament and held at least a share of the lead for the first three rounds.
“There’s no doubt that it was my week to win,” added the three-time major winner. “If you had followed me for the four days, I don’t think anyone would have questioned that my name was written on the trophy before the tournament started.
“I got the breaks all the way through. I hit some good shots and had a few breaks. Luck of the Irish? I’ll accept that.”
Last year’s champion KJ Choi shot a 68 to claim a share of eighth while Colin Montgomerie finished tied 11th after closing with a 69.
Meanwhile, race car enthusiast Richard Green took the chequered flag in the Portugal Masters but only after his rivals all crashed off the Vilamoura course.
The Aussie snatched 11 birdies in a final round 65 to win by two strokes with an 18-under par tally on the Oceanico Victoria course.
Green had a 90-minute wait with all 18 players ahead of him out on the golf course faltering in some form or another.
Among them was overnight leader, Pablo Martin of Spain, who blew a three-stroke final round lead to post a 75 and finish tied with Ireland’s Peter Lawrie in a share of sixth.
Earlier this year, Green drove his 996 GT Porsche Carrera to fourth place in a support race at the Australian F1 Grand Prix in his hometown of Melbourne.
And with his €500,000 first prize cheque, Green’s planning a €110,000 upgrade to the 1997 model.
Four players – Italian Ryder Cup star, Francesco Molinari (62), Spain’s Gonzalo Fernandez-Castano (68), Sweden’s Robert Karlsson (67) and Dutchman Joost Luiten (69) – were second on 16-under par.
Lawrie recorded his seventh top-10 this year but disappointed in ending just one stroke away from a tie for third after a closing round 69 for a 15-under par tally.
He birdied his opening two holes and while he had four other birdies, it was a three-putt bogey from just four feet at the fourth hole, and a bogey at the 11th that ruined hopes of only a second top-three of the year.
“A had a good chance today to go really low, but the bogeys at four and the 11th just killed me,” he said. “I couldn’t believe the bounce my ball took at 11 and that’s always a bit of a kick in the backside.”