Claxton finished at 18-under-par 270, one clear of James Driscoll (66) and Jaco Van Zyl (68), who shared the lead after three rounds with Claxton and Patrick Sheehan.
With the victory, Claxton became the first player in Nationwide Tour history to crack the $1 million barrier in career earnings.
Jon Mills took fourth place at 15-under-par 273 thanks to a closing 69 at The Country Club at Woodmore.
The 39-year-old Claxton and Van Zyl were near the top of a crowded leaderboard throughout the round. Van Zyl tripped to a bogey on the second, but recovered that stroke with a birdie on four. Claxton also birdied the fourth to move to 14 under.
Van Zyl birdied the sixth and eighth, but Claxton kept pace with birdies at seven and eight. The South African Van Zyl birdied the par-3 12th to forge a tie at minus-16.
Claxton pulled one clear at 17 under with a birdie on the 13th. Van Zyl moved back into a tie thanks to a birdie on the 14th.
Driscoll, who was playing three groups ahead of the leaders, was 2-under through 10 holes with eight pars and a pair of birdies. He moved to 15 under thanks to an eagle on the par-5 11th.
The 29-year-old Driscoll, who won the 2004 Virginia Beach Open, closed with back-to-back birdies to finish at 17-under and grab a piece of the lead.
Claxton responded with a birdie at the par-4 17th to move one ahead. He parred the last to secure his first tour win since he was victorious at the 2001 Louisiana Open.
Van Zyl could not respond as he parred the final three holes to post his best Nationwide Tour finish.
Nick Flanagan, who has won twice on tour this season, closed with a 6-under 66. He shared fifth place at 14-under-par 274 with Kyle Thompson (70), Matthew Jones (67), Matt Weibring (68) and Esteban Toledo (70).
Omar Uresti, who won the Livermore Valley Wine Country Championship, and Brenden Pappas were one stroke further back at minus-13.
Sheehan struggled to a 2-over 74 Sunday. He tumbled into a share of 14th at 11-under-par 277.