Gamez completed the event at 18-under-par 262. The win was his third on the PGA Tour and his first in over 15 years. He won in his first official start on the PGA Tour at the Tucson Open, then that same year, won at the Nestle Invitational in March of 1990.
'It feels great. I have a lot of family here, it's just a great feeling,' said Gamez, who claimed $630,000 for the win. 'I hit it great all day. I just kind of hung in and hit some good putts that didn't go in and in the end made a few on the back nine there.'
Olin Browne, who won three weeks ago at the Deutsche Bank Championship, closed with a 64 of his own to end three strokes back at minus-15. Mark Wilson and third-round leader Woody Austin shared third place at 14-under-par 266.
Bob Heintz and J.J. Henry each carded rounds of 2-under 68 to tie for fifth place at 13-under-par 267.
Gamez came flying out of the gate with a birdie at the first. He made it two straight as his second shot to the par-4 second stopped within 3 feet of the cup on the Resort Course at LaCantera Golf Club.
The 37-year-old was not finished. Gamez drained a 4-foot birdie putt on three to move to 15 under and three strokes clear of four players.
'I was really focused today and got off to a good practice session and hit some good shots on the range,' Gamez said. 'I started really quick. I hit it close on two and three and made a great putt on the first hole.'
Gamez cooled off as he parred his next seven holes around the turn. He dropped his second shot just inside 10 feet at the 11th and sank that to regain a one-shot lead over Browne, who had caught him at minus-15.
After a par on 12, Gamez knocked his approach to 8 feet at the 13th. He sank that effort and similar one on the next to get to 18 under. He parred out for the win.
'I played great. I missed two greens, 17 and five, and they were both on the fringe,' Gamez said. 'Everything else was close. I never really struggled to make good pars.'
Browne, a three-time winner on the PGA Tour, opened with a birdie on the first. He came back with a birdie on six and made it two straight with a birdie on seven.
The 46-year-old got to 13 under with a birdie on the ninth. Browne converted a birdie putt on the 12th to keep rolling. He then dropped in a 7-foot birdie try on the 14th to move into a share of the lead with Gamez.
However, Browne could only manage par on his last four holes to end three shots shy of the winner.
Dean Wilson, the second-round leader, closed with his second straight round of even-par 70. He ended alone in seventh place at 12-under-par 268. Jay Delsing, Harrison Frazar, Steve Lowery, Jeff Maggert and John Senden ended one stroke further back at minus-11.
Bart Bryant, last year's champion, posted a 4-under 66 in the final round to finish at 10-under-par 270. He was joined there by Heath Slocum, who closed with a 5-under 65.