David Mathis, who began the final round five ahead of Harris, struggled to a final-round 76 and tied for second place with Brian Guetz and Jon Turcott, both of whom shot rounds of 4-under 68. The trio finished at 8-under-par 280 at Thundering Waters Golf Club.
Harris played 32 holes on Sunday after an eight-hour weather delay backed the tournament up significantly.
Four players were tied for the lead at 8 under par, but Mathis broke out of the pack. At the 17th, Harris drained a 25-foot birdie putt to move one ahead.
Harris found trouble off the tee at the par-5 18th and he played smartly, laying up short of the green. His third, a wedge from 88 yards, nearly went in the cup for an eagle, but he settled for a tap-in birdie and his second win on tour after taking the Bay Mills Open Players Championship.
'I honestly thought it was over,' admitted Harris. 'I didn't think I could come back, to be honest. It turned out to be a sprint to the finish. I guess that's the way I operate.'
Harris won the Canadian Tour's money title and has been on a serious roll. He has won six events worldwide in the last two months and even tied for 21st last week at the Canadian Open on the PGA Tour.
'You look at the last five weeks, and it's been unbelievable,' said Harris. 'It's just a matter of putting the game in perspective. When you consider that I almost put the clubs away for good, it's really amazing. It's been quite the summer.'
Ken Duke, who was in the field on a sponsor's exemption, shot a 2-under 70 and finished alone in fifth place at minus-seven. Wes Heffernan fired a 4-under 68 and took sixth at 6-under-par 282.
Jamie Gomez posted a 5-under 67 for a seventh-place finish at minus-5, while Bryan Novoa (70), Brian Unk (72) and Stephen Woodard (70) shared eighth place at 3-under-par 285.