The world number one eased to a three-under par final round of 68, finishing on 17-under for the tournament after shooting in the 60s on all four days.
“It’s a pretty special feeling. It was a tough week,” said Scheffler, after becoming the first player in over 100 years to win his first four major titles by three strokes or more.
“I battled hard all weekend. It was a battle, but I played some really good golf and I’m fortunate to be standing here holding the trophy.”
It was the 10th successive time Scheffler has converted a 54-hole lead into a win.
His dominance over the past two years has been such that once he birdied the first hole, it seemed as though the chasing pack had already lost any belief of challenging.
Scheffler, who took a lead he would never relinquish with a seven-under 64 on Friday, extended his run of successive top-10 finishes to 11 events.
That streak now features four wins, including the PGA Championship and British Open titles.
The American, who led by four shots overnight, became only the second world number one to lift the Claret Jug after Tiger Woods, completing the third leg of a possible career Grand Slam.
Harris English finished in a distant second place, ending the tournament on 13-under courtesy of a closing round of 66.
Chris Gotterup completed a dream fortnight after last weekend’s Scottish Open triumph, carding a 67 to end a shot further behind in third.
Home favourite Rory McIlroy could not launch a serious charge, with his challenge finally snuffed out by a double-bogey on the 10th hole.
He had to settle for a tie for seventh place on 10-under and a standing ovation from his thousands of fans surrounding the 18th green.
“None of us could live with what he (Scheffler) had this week, but for me to be in front of everyone here at home and to get that reception up the last, absolutely incredible,” said Masters champion McIlroy. (AFP)