Tied for the lead overnight with Britain's Justin Rose in the PGA Tour's final playoff event, Snedeker birdied three of the last six holes to clinch his fourth title on the US circuit and his second of the year.
Snedeker, one of five players who came into this week knowing that victory would automatically secure him the playoff crown, signed off with a two-under-par 68 on a sun-splashed day at East Lake Golf Club for a 10-under total of 270.
After chipping in from the front of the green at the 17th for his fifth birdie of the day, the 31-year-old could afford the luxury of a bogey at the tricky par-three 18th where his tee shot sailed long into a grandstand.
"This has been an unbelievable week," Snedeker smiled after being presented with the two trophies. "The golf course is in great shape and obviously I liked it. At the end of the day, I had complete confidence of what I was doing out here."
Englishman Rose, playing with Snedeker in the final pairing on a difficult day for scoring in breezy conditions, finished alone in second after closing with a 71.
Moore, who had surged into a tie for the lead with three holes to play, bogeyed 16, 17 and the last for a 70 to tie for third at six under with Britain's Luke Donald (67).
World number one Rory McIlroy and second-ranked Tiger Woods, who like Snedeker had victory in their sights to complete the FedExCup 'double', both finished poorly.
Northern Irishman McIlroy, winner of the two previous playoff events, hit only two of 14 fairways on the way to a 74 and a share of 10th place.
"I'm a little disappointed to be honest," said the 23-year-old Northern Irishman who had been seeking a fifth PGA Tour victory this year and his fourth in just five starts.
"I didn't play the way I wanted to, especially today. I only hit two fairways, and you can't do that around this place."
Woods, who has twice landed FedExCup honours, closed with an erratic 72 to finish joint eighth at two under.
"I fought very hard just to shoot what I shot on the last couple of days," said Woods. "I shot under par (overall), but, obviously, not enough.
"My short game was really dialled in this week. I chipped and putted really well. I need to hit the ball a little better than I hit it certainly this weekend."
Snedeker's double triumph capped a storming late season run that began with his tie for third at the British Open in July where he opened with scores of 66 and 64.
He finished second and sixth in the first two playoff events to earn himself a wildcard selection for next week's Ryder Cup, and underlined his likely value to the US team with a stunning display of putting at East Lake.
With a massive pay-day looming large in the final round, Snedeker moved into the outright lead at nine under when he rolled in a nine-footer to birdie the par-four third.
Though he emulated Woods and McIlroy by double-bogeying the daunting par-three sixth, after hitting his tee shot into water, he remained a stroke in front at seven under.
Snedeker, widely regarded as one of the best putters in the game, drained a 40-foot birdie putt at the eighth before parring the ninth to reach the turn two shots clear.
He did well to save par at the 10th, coolly sinking an 11-footer, before Rose and Moore moved within a stroke of the lead with birdies at the par-three 11th.
However Snedeker sank another bomb, this time an 18-footer, to birdie the 13th and regain a two-shot cushion, prompting a vigorous fist pump in celebration.
Though Moore briefly caught him in a two-way tie at the top with birdies at 14 and 15, Snedeker pulled ahead for good with a two-putt birdie at the par-five 15th.
