Stadler fired a 9-under 63 in Sunday's final round to win the tournament, his 13th on the PGA Tour, at 21-under-par 267.
'I didn't even consider coming back from eight strokes down,' said Stadler, who earned $540,000 for his first victory since the 1996 Nissan Open. 'This is an awesome week. My son Chris caddied for me and Kevin (his son) also played in the event.'
Stadler became only the second player to win on the Champions Tour and PGA Tour in the same season. He captured last week's Senior Players Championship for his first win on the elder circuit and this week it's the B.C. Open.
Overnight leader Steve Lowery and Alex Cejka shared second place at 20-under par. Rod Pampling shot a 6-under 66 on Sunday to finish alone in fourth place at minus-19.
Stadler flew into red figures early with a 30-foot birdie putt at the first. He added a tap-in birdie at the par-5 third and made it two in a row with a 35-footer at the next.
Stadler reached the par-5 fifth green in two and two-putted for his third birdie in a row and fourth in five holes. He parred No. 6 but immediately went back to collecting birdies with a 47-footer at the par-3 seventh. Stadler sank a seven-foot birdie putt at the eighth to reach 18-under par.
On the par-5 12th, Stadler drained a 37-foot eagle putt to get to 20-under par. Now, Stadler felt he was ready to contend for his second trophy in as many weeks.
'I didn't start thinking about winning until I made the putt at No. 12,' said Stadler, who won the Masters in 1982. 'You have to shoot low on the front nine here.'
Stadler holed an eight-foot birdie putt at the 15th to remain in first but problems loomed for the recently turned 50-year-old. At the par-3 17th, Stadler looked in good shape when he landed his tee ball 10 feet from the hole but he three-putted for a bogey.
At the 18th, Stadler knocked a sand-wedge seven feet from the hole to set up birdie. Cejka, four groups behind Stadler, drained a 12-foot birdie putt at the 16th to match Stadler in first place.
Cejka drove into a water hazard for the second time in as many days on Sunday. He took his penalty drop and played his approach to 26 feet. Cejka's par putt missed the hole short by a few inches and after Lowery failed to hole his second shot at 18, the title was Stadler's.
'I truly expected Steve to shoot 4- or 5-under today,' said Stadler. 'I think you have to shoot 2- or 3-under on the front each day to have a chance.'
Lowery got nothing going on Sunday. He managed an even-par 72 and failed to earn his first victory since a win at the 2000 Southern Farm Bureau Classic.
For Cejka, his 5-under-par 67 on Sunday was not enough to break into the winner's circle. He collected six birdies and an eagle before his birdie at 16 tied him for the lead.
'Overall, I'm very pleased with how I played,' said Cejka, who previous best finish on the PGA Tour was a tie for seventh at this year's Phoenix Open. 'I was trying to play as good as I could. It hurts when you get this close.'
Mike Grob (64), Glen Day (66), Steve Allan (67), John Maginnes (69), Hank Kuehne (66) and John E. Morgan (70) shared fifth place at 17-under-par 271.