He closed with a three-under 67 for a two-shot victory and became the first player since Tiger Woods (2006-07) to win at least five times on the PGA Tour in consecutive years.
Scheffler leads the 30 players who advanced to the Tour Championship and has a chance to become the first repeat FedEx Cup champion since the series began in 2007.
All can win the $US10 million ($A15 million) first-place check, but there won't be any Australians competing at East Lake.
Former world No.1 Jason Day, the only Aussie in the Maryland field who started the final round in projected 36th spot, up from 44 at the start of the tournament, finished joint-23rd at one over after a final-round 73.
Day birdied the two par-5s, the fourth and 16th, but five bogeys - all on par-4s - saw him drop to 41st in the rankings and out of contention.
Third-round leader Robert MacIntyre didn't make a birdie until the 16th hole but pulled within one shot going to the 17th, the toughest hole at Caves Valley. Scheffler went just left in the rough, the ball sitting up nicely but the shot still scary.
He landed it some 60 feet short and watched it trickle, and then roll, and then slow again until it dropped into the cup.
"It looked good when it landed, looked good when it was rolling, and it was nice to see that one go in," Scheffler said.
MacIntyre could only look at him and stare at the world's No.1 player making other-worldly shots in another extraordinary season. MacIntyre (73), who made 18 birdies in the first 45 holes of the tournament, made only two over the last 27 holes.
Harry Hall, the only player who played his way into the top 30 on Sunday, made bogey on the par-5 16th — the easiest hole on the course — and then went long and left at 17. He also chipped in for birdie and was safe going up the 18th.
Rickie Fowler was on the verge of getting back to East Lake only to bogey the 14th and double bogey 15, knocking him out of the top 30 and replaced by Akshay Bhatia.
On the opening hole, Scheffler drilled his drive down the middle and hit to six feet for birdie, while MacIntyre missed the fairway and a six-foot par putt.
MacIntyre made bogey at the second and went from the fairway to a bunker on the short par-4 fifth, a two-shot swing when the Scotsman failed to get up-and-down for par and Scheffler made birdie.
And then Scheffler took the lead with a wedge to six feet for birdie on No.7.
Scheffler missed birdie chances at No.8 and 10. He botched a simple up-and-down at the 12th and three-putted from 18 feet on the 14th. Each chance kept MacIntyre in the hunt.
But then came one chip on the 17th, a knockout punch.
Scheffler, who finished at 15-under 265, has 18 career titles in the last three-and-a-half years since his first PGA Tour title in Phoenix.
With AAP.
