Brett Wetterich climbed into a share of third place with a seven-under 65. Wetterich shared third place at 12-under-par 276 with Jimmy Walker, who closed with a six-under 66. Hunter Haas ended in fifth place at 10-under-par 278.
On the playoff hole, both players found the rough off the tee. Bohn's second shot caught a tree limb. Couch, meanwhile, ripped his second shot within 20 yards of the putting surface. Bohn's third shot came up short of the green before he pitched his fourth close to the cup.
Couch knocked his chip shot within four feet of the hole and calmly sank the birdie try for the win.
'I hit the last putt dead center,' said Couch, who picks up $81,000 for the victory. 'It felt so good to see it go in the hole. I wanted to win this so bad I could taste it.'
Couch, who held a share of the lead after each of the first two rounds, got going with an eagle at the par-five fifth and followed that with a birdie at the next. The birdie briefly gave him a share of the lead.
The 2001 Florida Classic winner faltered to a bogey at the seventh. He came right back to sink consecutive birdies from the eighth to grab the lead at minus-15.
Bohn, who chipped in for eagle on the 18th to take the lead after three rounds, meanwhile dropped to minus-13 with a bogey at the seventh.
Couch found trouble on the back nine. He stumbled to a bogey at the 11th and dropped another stroke at the next to fall to minus-13. Bohn remained one stroke back though as he bogeyed the 12th.
Couch rebounded from his mistakes with a birdie at the 13th. He later carded another birdie at the 17th. However, he bogeyed the par-five last to finish at minus-14.
Bohn, needing to eagle the final hole, knocked his two-iron approach shot to 20 feet from the hole and drained the eagle putt.
'Every win out here is important because it gives you five years of great status,' said Couch, who moved into the top-20 on the Nationwide Tour money list. 'I go from conditional status to fully-exempt status with the win. But now I've got to play solid the rest of the year to reach my ultimate goal.'
Bohn was happy with the shot he hit to force the playoff, but wasn't disappointed in the loss.
'The two-iron was one of the best shots I've ever hit,' said Bohn, in reference to his second shot on the 18th. 'Then on the putt when I saw it halfway there I thought, 'This is going in.' I got pretty excited. Win or lose in a playoff, I feel like I played 72 good holes of golf. Hats off to Chris for getting the win.'
Ryuji Imada and Ted Purdy shard sixth place at nine-under-par 279. Jason Dufner, Kevin Durkin and Bubba Watson were one stroke further back at minus- eight.