Stadler, who also birdied the 72nd hole to get into the playoff, closed with a 2-under 68 to join Mathew Goggin, Kyle Thompson and Chris Tidland at 11-under-par 269.
The quartet returned to the 18th tee for the first extra hole. All four players found the fairway off the tee, but just Stadler and Thompson found the putting surface with their second shots. Tidland came up short, left in a bunker. He got up-and-down for this par. Goggin, also short and left of the green, but in heavy rough, pitched his third to 15 feet. He missed his par-save and was eliminated as Stadler and Thompson each two-putted for par.
The three remaining players moved to No. 10. Tidland and Stadler hit the fairway off the tee and the green with their second shots. Thompson, hitting his second from the short stuff, missed the green with his second. His pitch rolled some 20 feet passed the cup, then his par putt missed badly. The bogey knocked him out of the playoff, as Stadler and Tidland both two-putted for par.
The final two players moved to the par-5 16th. Tidland and Stadler both ripped their drives down the middle off the tee. Tidland's second came to rest in the rough short, left of the green. Stadler, who won the Lake Erie Charity Classic two weeks ago, knocked a fairway-wood on to the putting surface about 35 feet from the cup.
Tidland pitched 8 feet passed the cup with his third. Stadler, son of Champions Tour player Craig Stadler, lagged his eagle putt to tap-in in range. He kicked in the birdie putt and watched to see what Tidland would do.
Tidland's birdie try to extend the playoff missed the cup left and Stadler picked up his second playoff win in three weeks. The victory also earns him a spot in the U.S. Bank Championship in Milwaukee in two weeks. Stadler will join his father at the B.C. Open next week on the PGA Tour.
Stadler second victory came in just his fourth career start, an all-time record. Dick Mast held the previous record when he notched two wins in his first six career starts in 1990.
'It still hasn't sunk in from two weeks ago,' said Stadler, who earned $85,500 for the win. 'To win one was beyond my expectations, but to win two is beyond words. The last four weeks have been incredible to say the least.'
Stadler opened his round with three birdies and a bogey over his first five holes. After back-to-back bogeys from the 14th, the 24-year-old Stadler climbed back to minus-11 with birdies at the 16th and 18th.
'I knew I had to make birdie on the last hole of regulation,' Stadler said. 'Obviously I would have like to win in regulation, but standing on No. 18 I was begging for a playoff. My chances were slim after the bogey on No. 15.'
Thompson, who shared the third-round lead with Tidland and Stadler, posted two bogeys and four birdies in a round of 68 to join the playoff.
Tidland, looking for his first win, birdied two of his first three holes. After seven straight pars, he posted two bogeys and two birdies on the back side to end at minus-11 after a closing 68. The playoff loss was his second in two years on tour.
'I gave one way on 16 today,' said Tidland. 'I thought my 3-wood on 16 during the playoff was my best shot of the day.'
Goggin made the biggest move of the day to gain entry into the playoff. He birdied the first, then eagled the par-4 fourth. Goggin came right back with birdies at the fifth and sixth. He picked up another birdie at the ninth before two birdies and two bogeys on the back nine gave him a closing 64.
'It's disappointing. I blew the tournament on Saturday,' said Goggin. 'I three-putted from 15 feet twice on Saturday. I just started too far behind the leaders today.'
Jason Caron closed with a 68 to end alone in fifth place at 10-under-par 270. Ryuji Imada and Darron Stiles shared sixth place at 8-under-par 272 with Rick Fehr and Johnson Wagner one stroke further back at minus-7.