Wang started strongly with four birdies on the front nine at the 6,624-yard course at the Macau Golf and Country Club, but slipped on the back nine with consecutive bogeys on the par-5, 12th and 13th holes.
The veteran golfer stayed on par for the rest of the course, sealing his win with a four-round total of 270.
'At my age, it feels great to win again,' Wang said. 'It's not often that golfers can win when they are 42. I hope it won't be another six years before I win again.'
Australia's Marcus Both finished with a 5-under 66 and compatriot Jarrod Lyle shot a 67 to finish at joint second at 13-under 271.
'I went out there today and did everything I wanted to do,' said Lyle. 'I was very aggressive but it probably didn't pay off on 12 when I made a double bogey.'
Defending champion Jason Knutzon (70) shot three birdies against two bogeys to end four strokes off the pace at 274 with fellow American Edward Loar and Australian Terry Pilkadaris.
China's Zhang Lianwei, a two-time Macau Open champion, shot an impressive 6-under 65 on the back of seven birdies to join American Corey Harris, South Korea's Suk Jong-yul and India's Arjun Singh with 278.
Former U.S. Masters champion Fred Couples made an eagle on the par-5 18th hole, but also shot three bogeys and a double bogey for a final round 70, nine strokes off the lead.
'It's been a fun week. But it was a bit too erratic this week for me to have really challenged. It was tough out there with the heat and wind but I've had a good time,' said Couples, who tied for second at the SK Telecom Open in South Korea last week. 'I enjoyed playing golf in Asia for the past two weeks.'
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