The 32-year-old Moore, who won the Richmond Open as a Monday qualifier six weeks ago, earned a check worth $76,500 for the second time this season.
'The first win in Richmond was special and it always will be, but this one kind of validates that the first one wasn't just luck,' he said. 'All I ever wanted was an opportunity to play. I just wanted a chance to prove that I could play.'
One more victory and Moore will get a shot at the big leagues. Any Buy.com Tour player who wins three times in a season earns an immediate promotion to the PGA Tour.
Hunter Haas, the 1999 U.S. Amateur Public Links champion, shot an even-par 71 at the Upper Course at Peek 'n Peak Resort to finish second at eight-under.
Kelly Gibson and Doug Barron, who both shared the lead after 54 holes with Haas, turned in one-over 72s and wound up in third place at seven-under 277 with Andrew McLardy (69), Tyler Williamson (70) and second-round leader Omar Uresti.
Uresti opened with back-to-back 67s but struggled to a 77 in the third round to slip into a tie for 26th place. He rebounded on Sunday with the day's best round of five-under 66.
Haas rang up three birdies over the first five holes to reach 11-under, but bogeyed the sixth, ninth, 10th and 13th to back up to seven-under. Although he sank a birdie at the 17th hole to pull within one of Moore, who was already in the clubhouse, Haas failed to force a playoff when he missed a 15-foot birdie putt on the 18th green.
Gibson made a pair of early birdies but dropped to one-over for the day at the turn after suffering a double-bogey at the seventh and a bogey at the eighth.
Barron seemed headed for a runaway win when he birdied four of the first eight holes to take a two-shot lead at 12-under par. But he carded a quadruple-bogey eight on the 500-yard, par-four ninth, where he twice visited the woods lining the fairway before missing an eight-foot putt that would have limited the damage to a triple.
Barron was still in the mix at eight-under, that is until he bogeyed the par- five 17th and closed with a par at 18.
Moore made it to eight-under with birdies at the first and third holes. After a run of 13 straight pars he two-putted from long range for birdie at 17, which proved to be the difference.
Ben Bates (71) and Anthony Painter (71) tied for eighth place at minus six.