Competing for the first time in more than five months, and playing on his home course, Na finished at 16-under-par 268 following his third round in the 60s this week.
The only thing keeping the PGA TOUR regular from breaking tournament scoring record was a two-putt double-bogey at Empire Lakes Golf Course's 18th hole.
His win almost inevitable since opening with a course-record-tying 62 on Thursday, Na finished one shot shy of tying the tournament record of 267 held by four players.
'Playing on my home course was a huge advantage this week,' said Na, a Rancho Cucamonga resident. 'The course was playing so difficult. Most everyone today was near even-par, which shows how tough it was playing.'
Chris Tidland fired a 5-under 66 to move into a tie for second place with Jeff Quinney (71) at 13-under 271. Grant Waite was one shot further back at 272 following a 71.
Na was competing for the first time since late April, when he withdrew from the PGA's Shell Houston Open with a broken hand. Taking medication to dull the pain, he had been making starts since breaking the hand in a car door in January.
All that changed in Houston when Na, 23, finally decided he was doing more harm than good by playing.
Now, in a warm-up for his return to the PGA TOUR next week, Na is a first-time winner in only his second career Nationwide Tour start. Not to mention $90,000 richer.
'It is nice to have another win on the resume,' said Na, whose only other worldwide win came at the 2002 Volvo Masters of Asia. 'I played solid the whole week. I putted well and hit it well all week.'
Ken Duke had a 72 and finished fifth at 11-under 273. Tim O'Neal and Brett Bingham posted 68s and shared sixth place with Josh Broadaway (69), Tom Scherrer (70) and Ryan Armour (72) at 274.