DeChambeau, who shot a final-round 67, was the only player to break par in the last round and finished at 6-under. He toppled 21-year-old Matthew Wolff -- who was attempting to become the youngest U.S. Open champion since Bobby Jones in 1923 -- by six shots for his first major championship.
In six U.S. Opens at Winged Foot, DeChambeau became only the third player to finish the event under par. His 6-under 274 was the lowest, and he was the first to have four rounds at par or better at Winged Foot.
"As difficult as this golf course was presented, I played it beautifully," DeChambeau said. "Even through the rough, I was still able to manage my game and hit it to correct sides of the greens and kept plugging away. My putting was immaculate today. My speed control [was] incredible. That's why we worked so hard on my speed control.
"... For me, it's about the journey of can I execute every shot more repeatably than everybody else? I was able to do that this week. That's why I won by six."
Wolff closed with a 75 to finish at even-par 280. Louis Oosthuizen (73) ended up in third at 2-over 282, and Harris English (73) was fourth at 3-over par. Xander Schauffele finished fifth at 4-over.
Dustin Johnson -- who entered the tournament as the top-ranked player in the world -- shared sixth with Will Zalatoris at 5-over 285. Justin Thomas (72), Tony Finau (71), Rory McIlroy (75), Webb Simpson (73) and Zach Johnson (74) tied for eighth at 6-over par.