The 26-year-old Hadwin shot a 3-under 69 at Prince of Wales Country Club for a 16-under 272 total. He earned $117,000.
"I don't know what to say, I really don't know to feel, what to think," Hadwin said. "It's amazing. I battled all day and to finish birdie-birdie and make the putts I did on the last two holes gives me so much confidence. I couldn't be happier."
Presnell had three eagles, the last an 18-footer on the par-5 18th for a 68.
"I heard roars, but I didn't know what happened," Hadwin said. "I knew it was going to be close. I said to my caddie on 17 tee that, 'If I make two birdies, they can't catch us.' "
Hadwin got up-and-down from a greenside bunker on the 308-yard, par-4 17th to tie Presnell for the lead. From 230 yards on the 18th, he hit a 4-iron that missed the green, then chipped to 4 feet and made the putt.
"It was an awkward number. I wanted to hit 5-iron and didn't think I could clear the water if I missed it a little, so I went with 4," said Hadwin, a former University of Louisville player. "I guess I gave up on it a little and luckily it cleared the water. It was a fairly easy chip across the green and was able to get up and down for the victory."
He became the 13th Canadian-born player to win on the Web.com Tour and the first since Chris Baryla in the 2009 Chattanoonga Classic, a span of 111 tournaments.