McCarron closed with a 6-under 66. Steve Lowery rallied to finish alone in third place. He closed with a 5-under 67 to come in at 28-under-par 331.
Appleby and McCarron returned to the 18th tee at the TPC at Summerlin for the playoff. After good drives, Appleby knocked his second shot on the green. McCarron dropped his shot on the green as well, and spun it back, nearly hitting Appleby's ball.
Appleby was the first to putt and calmly ran in the birdie try. McCarron, who also had a chance to win on the last hole of regulation, was unable to make the putt thus giving the victory to Appleby.
'On No. 18, I had a look at the putt and as soon as I saw it, I thought I could roll it in,' Appleby said. 'I was very relieved it fell in the hole, but at the same time, I still had Scott's putt to take notice of. To my benefit, he just missed the putt.'
Appleby battled throughout the round with playing partners Steve Flesch and McCarron. The trio had moved to 28-under through eight holes. Appleby had spread two birdies and two bogeys out over those first eight holes, while McCarron birdied Nos. 4, 5 and 8, and Flesch had two birdies and a bogey to that point.
'Really No. 3 focused me back to the point where I need to do what I was doing the previous day,' said Appleby of the hole where he notched his first birdie on Sunday. 'To stay with the shots, pick the shot correctly. I liked the way I was reading the greens and how everything was feeling.'
Appleby, who shared second place here last year, and Flesch both birdied the ninth to move one stroke ahead, but McCarron created a three-way tie with a birdie on the 10th. After the trio all parred the 11th, some separation came at the 12th.
Appleby birdied the hole, while Flesch bogeyed and fell two shots back. He would not challenge again. McCarron, who parred the 12th, tied Appleby in the lead with a birdie on 13.
The duo both parred the 14th and birdied the 15th to maintain a three-stroke lead over Lowery. Appleby birdied the 16th to move ahead, but stumbled to a bogey at the next when his tee ball nearly found water.
'I was fortunate enough to hit the ball left and have it stay up,' said Appleby, who earns $720,000 for the win. 'I was really relieved that it stayed dry and I was thinking that is a good break and a nice thing to have happen.'
Both men parred the 18th hole, with McCarron's attempt for birdie and the win missing on the right side. So the pair returned to the 18th tee for the playoff.
'Stuart's ball stays up twice on the 17th hole, it was just his turn to win,' said McCarron.
Scott Verplank carded a 5-under 67 to finish alone in fourth place at 27-under-par 332. David Frost ended one stroke further back at minus-26.
Flesch bogeyed the 12th and 13th to fall off the pace and fell farther back with a double bogey on No. 16. He shared sixth place with Woody Austin at 25-under-par 334.