'It's fantastic. I've waited for this moment for a long time,' said Canonica, who became the 10th first-time winner on the European Tour in 2005.
Francesco Molinari posted a 3-under 69 and tied for sixth place with Wade Ormsby, who carded an even-par 72 on Sunday. The duo was knotted at minus- 4.
Canonica began the final round two shots behind Colsaerts, but made up the difference quickly. Colsaerts bogeyed the third and fifth holes, but Canonica established a lead for himself.
At the fourth, Canonica ran home a 5-foot birdie putt and added another birdie from 15 feet at the eighth. That gave the Italian a two-shot lead, but he missed a 7-footer for par at the 11th after he missed the fairway left.
Colsaerts was one back at the par-5 12th, but drew even with a birdie. Canonica missed his second shot right of the green at 12, but got up and down from 7 feet for birdie to reclaim a one-stroke cushion.
Canonica missed a right-to-left 10-footer for par at the 13th to allow most of the field back into the tournament. Colsaerts bogeyed the hole as well to remain one behind.
Canonica dropped yet another shot to par at 14 to fall into a share of the lead with Colsaerts, who only had 2 feet to save par at the same hole. He missed the putt falling into a tie for second with Lynn and Lane.
The Italian parred No. 15 to stay one ahead, but Colsaerts bogeyed and was two back.
Canonica looked like he was in trouble at the par-5 16th when his drive landed in the thick stuff on the left side. He hacked his second near the green, but the ball rolled toward a water hazard. The ball stayed up and he hit a beautiful pitch that ran 5 feet past the hole. Canonica converted the birdie try to move three clear.
'It was not a bad drive, the thick rough just opened the face,' said Canonica, referring to his second at 16. 'I had a very bad lie for my third shot and I made a great lob-wedge from there. It was a great four.'
Colsaerts birdied 16 to get back within two and with every other contender in the clubhouse, he posed the only threat to Canonica's title. Problem was, Colsaerts could not get anything going. He parred out his remaining holes, but Canonica gave everyone a sliver of hope at 18.
At the par-5 closing hole, Canonica took an iron off the tee and laid up with his second. Unfortunately, his second found the rough on the left. Canonica's third landed 20 feet from the hole and he calmly two-putted for the victory.
'I played very good this week,' said Canonica. 'My putting was so-so, but I'm happy with this result.'
Richard Bland (75), Raphael Jacquelin (68), Sam Little (71), Gary Orr (68) and Steve Webster (73) tied for eighth place at 3-under-par 285.