Nick Cassini finished alone in second place at 12-under-par 268 while overnight leader Mike Standly was one shot further back alongside Mario Tiziani at 11-under-par 269.
Carter became the first player to win three times on the Nationwide Tour in 2003 and in doing so he achieved the 'Battlefield Promotion' and will advance to the PGA Tour.
'I had all of my reservations made for the rest of the year, but I guess I'll have to change those now,' said Carter. 'My truck's in Denver and I'm not sure how or when I'll get it, but it's a nice predicament to have.'
Carter was two strokes behind Standly to start the day at The Links of Glen Eagles and collected three birdies over his first six holes to take sole possession of first.
'I'm a little surprised,' said Carter. 'I got off to that good start and Mike had a few bad bounces. I guess the momentum was in my favor from that point.'
While his competitors faltered around him, Carter continued his fine play on the back nine.
He added a birdie at the par-4 13th and finished in style with a birdie at the par-5 last.
'I was looking at the leaderboards today to see what was going on,' said Carter. 'After I hit my tee shot in the fairway on No. 17, I asked my caddie how we were doing. He told me we were up five at that point. It was nice to have some breathing room.'
Standly had a tough run on Sunday. The former PGA Tour winner double-bogeyed the second and added a bogey at the sixth to fall out of the lead.
The 39-year-old had a birdie and a bogey on the inward half for a round of 73.
Jeff Freeman, David Branshaw and John Morse tied for fifth at 10-under-par 270.
Blaine McCallister, Jeev Milkha Singh, Wade Ormsby and Daniel Chopra were two shots further back at 8-under-par 272.
Scott Dunlap, Scott Hend, Rob Johnson and Wes Martin shared 12th place at 7-under-par 273.