Kuehne shot a final-round 69 to finish regulation alongside Harris at 15-under-par 273, one stroke clear of Remi Bouchard and third-round leader Ken Duke.
Kuehne and Harris both parred the first playoff hole, the 18th, and the duo headed to the par-5 first to play a second extra hole. Kuehne nearly blasted his drive out of bounds as his ball came to land near the ladies tee on the 18th. He he hit his second shot to 12 feet, where he two-putted for birdie and the win.
'I was unbelievably lucky with that tee shot, but sometimes you need the breaks to win,' said Kuehne, who moved into first place in the 2002 Order of Merit (money tiltle) race. 'I knew I needed to play well here, and I am pleased I rose to the occasion.'
Kuehne is only one tournament away from capturing the Order of Merit title, which grants an exemption into the second stage of the PGA Tour Qualifying School.
'It feels like a big weight has been taken off me,' said Kuehne, who can also earn an exemption into the Air Canada Championship and Bell Canadian Open on the PGA Tour. 'This is what I have worked for all year. Anytime you can skip a week of Q-School, not to mention get into the PGA events up here, that's huge.'
The 1998 U.S. Amateur Champion, who picked up his first win of the year at the Texas Challenge in March, began the day one stroke behind overnight leader Duke. Kuehne was solid during the final round at Club de Golf Le Versant but he made his move late in the round to reach the playoff.
Kuehne birdied the 16th and 18th holes to enter the clubhouse with the lead at minus 15. Harris was also at 15-under with the par-4 18th remaining but he could do no better than par at the closing hole.
For Duke, the final-round outcome was almost a perfect reflection of last year's tournament. Duke had the lead coming home but eventual champion Paul Davenport ran home an 80-foot putt for eagle to match him at the last. Davenport went on to the playoff win while Duke was left with another near miss.
Davenport didn't have any late heroics this year. He carded a 68 to finish tied for sixth at 12-under-par 276 alongside David McKenzie.
Final results from the Telus Quebec Open