The 209-yard, par-3 fourth was just as important in the outcome.
Furyk took the lead there Sunday with a hole-in-one and played it in 5-under par for the week, while Singh bogeyed it and was 3 over in four rounds.
"Eight strokes, that's a huge turnaround on one hole," Furyk said. "It's pretty special to play the hole 5 under on the week. You usually do that on a par 5 and rarely or never see that on a par 3. A pretty darn good hole, too. It's not like a wedge or a 9-iron shot."
Furyk, the winner last year at traditional Hamilton Golf and Country Club, finished with a 7-under 64 for a one-stroke victory. He had a 16-under 268 total on Angus Glen's links-style North Course.
With the victory, Furyk's 13th on the PGA Tour and first since last September at Hamilton, he guaranteed the big name-starved event will have at least one top player next year at Glen Abbey.
"I'll be here," Furyk said. "I always think you should come back and defend a championship. ... I felt a lot of support out there."
Three strokes behind Singh after the third round, Furyk birdied two of the first three holes holing a 35-foot putt on the par-5 first and a 9-footer on the par-4 third before moving ahead at 13 under with his third career ace.
"You dream of a start like that," Furyk said.
Furyk used a 5-iron to attack the back-right pin position on No. 4, a hole he birdied the first three days. His ball landed in the fringe just over a large bunker and rolled about 30 feet straight into the hole.
"Tough pin on four," Furyk said. "To be able to fly a 5-iron back there on the fringe, have it release out and go in the hole is, obviously, a special bonus."
Singh's tee shot on No. 4 went 25 yards right and he dropped a shot after taking two more strokes to reach the putting surface.
Singh, the 2004 winner at Glen Abbey in a playoff with Canadian star Mike Weir, shot a 68. Ryan Palmer and George McNeill closed with 66s to tie for third at 13 under, and Bob Heintz (67) and Hunter Mahan (67) followed at 12 under.
Furyk took a two-stroke lead to the par-4 18th, but made it interesting by three-putting for a bogey. He missed a 5 1/2-footer for par, giving Singh playing two groups behind a chance to force a playoff with a birdie.
"Obviously, 18 was a slip-up," Furyk said. "And playing maybe a touch conservative away from the pin. I thought I actually hit a pretty good little second putt. I thought it was going in and it leaked out on me. ... I'm glad it didn't cost me."