Both Scott (71) and Moore (68) finished 72 holes at seven-under-par 273 after Scott had birdied the 18th to force the playoff.
The Australian missed two chances to win the playoff at the 17th and 18th holes, missing makeable putts before a dramatic final playoff hole, again at 18.
Scott put his drive into the bunker and left his approach shot short on the front portion of the green before he made the long birdie putt, which generated a big fist pump from the Aussie and howls of delight from the gallery.
|"I'll probably take more from this one, gutting it out, than winning by five."|
American Bart Bryant finished third on 277.
"This may not have been the message I wanted to send," Scott said of his sixth PGA victory.
"But any win is good.
"I'll probably take more from this one, gutting it out, than winning by five."
Looking for Moore
Moore, who is still seeking his first PGA Tour title, collected his third second place finish of his career.
"I'm disappointed I didn't make my putt after he made his. But I still got closer than I have in the past, losing in a playoff," Moore said.
Spain's Sergio Garcia finished tied for 19th on 281 and is still to record a top-10 finish this year.
He was six-over after five holes, but mixed four birdies with three bogeys for the rest of the round to finish with a 75.
"I am still encouraged with where I am," Garcia said.
"After the fifth hole I played well enough to win today.
"That's what I will take with me."