Scheffler, who also took the green jacket in 2022, won a record $3.6 million top prize after a drama-filled battle with fellow Americans Collin Morikawa and Max Homa and Sweden's Ludvig Aberg, who made an impressive major debut.
Scheffler birdied three of the last six holes to fire a four-under-par 68 and finish 72 holes over the iconic 7,555-yard layout on 11-under 277 with Aberg shooting 69 to finish second on 281.
Two-time major winner Morikawa had a closing 74 to share third on 284 with Homa and England's Tommy Fleetwood.
"Did my best to stay calm out there and to be patient," Scheffler said.
"They played well out there and I was fortunate to hold them off until the end."
Scheffler matched Tiger Woods as the only players to win the Masters twice while atop the world rankings.
He also became the fourth-youngest multiple Masters winner at age 27 behind Woods, Jack Nicklaus and the late Seve Ballesteros.
"Scottie is an amazing golfer," Homa said. "It's really impressive."
Scheffler, who hasn't played a round over par since last August, has the second-fewest Masters starts for any two-time winner with five. Only Horton Smith needed fewer, taking two of the first three Augusta titles in the 1930s.
Aberg pressured Scheffler down the stretch but could not catch him.
The performance was all the more remarkable as the American played with the added distraction of knowing he might have to return home at any moment to be with his wife for the birth of their first child.
"It's a very special time for both of us," said Scheffler, before last year's winner, Spaniard Jon Rahm, slipped the Green Jacket on him. "I can't put into words what it means to win this tournament again.
"I really can't put into words what it's going to be like to be a father for the first time.
Scheffler had seized a four-stroke edge but was short of the green at 11 and made a bogey while Aberg moved within two with a tap-in birdie at the par-5 13th.
After Scheffler sank a three-footer for birdie at 13 to reach 9-under, Aberg answered with a five-foot birdie putt at 14 to stay within two.
"It was a dream come true to be in this situation, to feel the pressure coming down the final holes," Aberg said.
Scheffler responded with a tap-in birdie at 14 and sank a nine-foot birdie putt at the par-3 16th to reach 11-under, all but sealing the victory.
Walking up to the 18th green, Scheffler was greeted by a standing ovation from spectators delighted by his skilled shotmaking.
A crucial streak of three birdies by Scheffler following a bogey at seven featured his most spectacular shot.
After a 10-foot birdie putt at the par-5 eighth, Scheffler lofted an incredible 89-yard second shot at the ninth that rolled down a slope within inches of the hole to set up a tap-in birdie for the solo lead as the crowd roared.
Scheffler added a nine-foot birdie putt at 10, reaching 9-under and boosting his lead to two shots while rivals suffered double-bogeys.
Morikawa made a double-bogey at the ninth after finding pine straw and a bunker and another at 11 dropped him out of contention.
"I got greedy on nine and 11. When you're playing good you get greedy," Morikawa said. "Greed got the best of us."
Aberg plunked his second shot at the 11th into a pond and made a double-bogey, sinking four adrift in his bid to become the first Masters winner in his debut since Fuzzy Zoeller in 1979.
"I came out very nervous. I was shaking on the first tee," Aberg said. "Hitting in the water on 11 wasn't ideal."
Homa, seeking his first major win, hit an unplayable ball into the flowers over the par-3 12th on the way to his double bogey.
Tiger eyes four majors
Well back were second-ranked Rory McIlroy, third-ranked defending champion Jon Rahm and 15-time major champion Woods.
Four-time major winner McIlroy, who needs only a Masters victory to complete a career grand slam, fired a 73 to finish on 292.
"Hasn't been my year this year but I'm going to keep coming back until it is my year," McIlroy said.
Spaniard Rahm made two double-bogeys on the back nine and fired a 76 to finish on 297.
Woods, whose 10-over 82 on Saturday was his worst-ever Masters round, closed with a 77 to finish on 16-over 304, last among 60 players to make the cut in his worst 72-hole Masters effort.
The 48-year-old legend, who has struggled to walk 72 holes since suffering severe leg injuries in a 2021 car crash, said he was planning to play all four majors this year.
"I'm going to do my homework going forward at Pinehurst, Valhalla and Troon," Woods said.
"Hopefully the next three my body will cooperate."
