The 28-year-old finished with a four-round aggregate of 24-under par 264 at Chendu's Luxehills International Country Club, earning himself a cheque for $512,505 and becoming only the second Belgian to notch a European Tour win.
Despite the pressure of bidding for his first victory, Colsaerts kept his head to run away with the title making six birdies and no bogeys for a final round 66.
Spain's Pablo Martin shot a 63 and New Zealand's Danny Lee carded a 65 to join Denmark's Soren Kjeldsen and Ireland's Peter Lawrie as joint runners-up at the co-sanctioned OneAsia and the European Tour event.
Korean teenager Han Chang-won, who was one stroke behind third round leader Colsaerts, dropped back on the final day to return a 74 and 273 overall.
Colsaerts first made it onto the European Tour in 2000 as a 18-year-old at the Qualifying School, but it was not until 2009 that he started to make real progress in the professional game, twice winning on the Challenge Tour.
"I have been waiting a long time for this and so I am pleased I won in such a good way," he said. "A lot of people expected me to win a lot of events but it has not been that easy. It has been a hell of a journey."
The Belgian was ranked the biggest hitter on the European Tour last year and took full advantage of the wide fairways and lack of rough at Luxehills.
Han, the 2009 Asian Amateur Champion, made a double bogey six on the eighth and reached the turn in one over par 37 to fall out of the running.
"There was a lot more pressure today playing in the final group. It was very different from the first three days. I found it hard to settle down but I have learned a lot," said Han.
China's Liang Wenchong, who won the Luxehills Chengdu Open here last year on OneAsia, closed with a 71 to finish the tournament 11-under-par.
The next OneAsia event is the GS Caltex Maekyung Open at Namseoul Golf and Country Club just outside of Seoul in Korea starting on May 5.
Leading scores from the Volvo China Open at Luxehills International Country Club in Chengdu after the final round on Sunday (Par 72):
264 - Nicolas Colsaerts (BEL) 65 67 66 66
268 - Pablo Martin (ESP) 70 68 67 63, Danny Lee (NZL) 66 68 69 65, Soren Kjeldsen (DEN) 65 71 66 66, Peter Lawrie (IRL) 68 64 68 68
269 - Christian Nilsson (SWE) 70 65 70 64
270 - Danny Willett (ENG) 70 66 69 65, Jamie Donaldson (WAL) 70 61 70 69, Gregory Havret (FRA) 66 66 68 70
271 - Richard Finch (ENG) 69 67 71 64, Pablo Larrazabal (ESP) 70 67 70 64, Gareth Maybin (NIR) 65 67 72 67, Jeev Milkha Singh (IND) 66 66 71 68, Aaron Townsend (AUS) 68 66 68 69
272 - Joost Luiten (NED) 66 67 71 68
273 - Peter Whiteford (SCO) 67 68 70 68, Anthony Brown (AUS) 67 71 67 68, Michael Jonzon (SWE) 67 68 69 69, Bradley Dredge (WAL) 65 70 69 69, Keith Horne (RSA) 63 69 70 71, Han Chang-won (KOR) 64 70 65 74
Selected:
274 - Sergio Garcia (ESP) 66 67 72 69
276 - Zhang Lianwei (CHN) 71 68 70 67
277 - Liang Wenchong (CHN) 68 66 72 71, Andre Stolz
(AUS) 68 68 67 74