'People always talk about getting in the zone and I found it today,' said Quinney, a Eugene, Oregon native. 'Somehow it all fell together today. It is the round of my life I guess you would call it, but I don't feel like I did anything out of the ordinary.'
Barry Cheesman climbed into a tie for second at 10-under-par 278 with a closing 68. He was joined there by David McKenzie, who posted a 3-under 69 in the final round.
Third-round leader Jason Schultz ended one stroke further back at minus-9 alongside Jason Gore. Schultz was attempting to be the first wire-to-wire winner this year on the Nationwide Tour.
Quinney's stellar front nine proved to be the difference. He dropped in a birdie at the second and came right back to birdie the third.
The 25-year-old picked up his first eagle of the event at the par-5 fifth to jump to minus-8. He followed that up with a birdie at the very next hole at Shadow Hills Country Club.
Quinney, the 2000 U.S. Amateur champion, kept moving up as he birdied the seventh to play the opening seven holes in 6 under par. He settled down to card seven pars in a row around the turn.
The Arizona State graduate took the lead when he collected his second eagle of the round at the par-5 15th, draining a 30-footer to get to minus-12. Quinney picked up a birdie on 17 before a par at the last hole.
'Obviously having your first win come in your hometown in front of family and friends makes it really special,' Quinney said. 'It can't get any better than this. When the putt went in on No. 15, it sent a little jolt in my system. The putts managed to fall today. I knew it was going to be a special day when I was six-under after the first seven holes.'
Cheesman kept pace early on with Quinney. He birdied the second and third to get to minus-8, but was derailed by a bogey at the fourth. He played his next 10 holes at even par, swapping a birdie for a bogey at the Nos. 9 and 10.
Cheesman, a two-time winner on the Nationwide Tour, birdied the 15th, but tripped to a bogey at the next. He closed with a birdie on 17 and an eagle at the last to share second place.
McKenzie opened with a birdie on the second, but faltered to bogeys at three and seven. He collected four birdies on the inward nine to share second with Cheesman.
David Hearn and Michael Long shared sixth place at 8-under-par 280. Doug Barron, Paul Gow, Scott Petersen and Brandt Snedeker were one stroke further back at minus-7.