The 23-year-old former US Amateur champion finished birdie-birdie to pip Patrick Rodgers, emulating Jordan Spieth by claiming a first PGA Tour triumph in this event.
Spieth’s success in 2013 go him into The Open at Muirfield and now DeChambeau will also get his first taste of golf’s oldest major in this week’s 146th staging of the event as the John Deere Classic champion.
DeChambeau, a colourful character who last played on British soil in the 2015 Walker Cup at Royal Lytham, had a chance to play last year at Royal Troon but gave that up when he turned professional.
“It’s pretty special to play in an Open Championship, the home of golf pretty much, where golf started,” he said. “It’s pretty special to have that first time.”
DeChambeau closed with a six-under 65 to finish on 18-under, one ahead of Rodgers (70) after he dropped a shot at the 17th.
Earlier on Sunday, Callum Shinkwin, Matthieu Pavon and Andrew Dodt also secured Birkdale spots through the Aberdeen Asset Management Scottish Open at Dundonald Links.
Korea’s Sung Hyun Park us the new US Women’s Open champion after landing her first LPGA Tour title in style at Trump National in New Jersey.
The 23-year-old Korean closed with a five-under-par 67 to finish on 11-under, two ahead of compatriot Hye Jin Choi, who was bidding to become the first amateur in 50 years to win the event.
“I did not have the best first and second rounds,” said Park, who opened with 73-70 before storming to the top of the leaderboard in Bedminster with a brace of 67s.
“I wanted to believe in myself again for the final two rounds and I did.”
Choi’s title hopes were killed off after the 17-year-old found water at the 16th in her closing 71.
World No 1 So Yeon Ryu tied for third, four shots behind the winner, with fellow Korean Mi Jung Hur.
China’s Shanshan Fang, who led after each of the first three rounds, had to settle for joint-seventh after a closing 75 that included a triple-bogey 8 at the last.
Catriona Matthew finished joint-44th on six-over after a closing 72 with Charley Hull tying for 21st after a last-day 73.
Bernhard Langer missed out on fourth successive Constellation Senior Players Championship after running up a double-bogey 17th in the final round.
The uncharateristic slip up from the German saw him pipped for the title at Caves Valley Golf Club in Baltimore by American Scott McCarron.
Langer’s closing 73 gave him a 17-under-par total, one behind McCarron after he finished with a 66, set up by him racing to the turn in 31.
“This is going to hurt for a little while because it was within my grasp to win the championship,” said Langer, who was bidding for his third over-50s major of the year.
“All I had to do was come home in even par more or less. Twenty under would have done it. But it’s easier said than done.”
Miguel Angel Jimenez was fourth on 16-under while Colin Montgomerie closed with a 68 to finish joint-sixth on 11-under.
Blairgowrie’s Bradley Neil is up to seventh in the Road to Oman with earnings of just under £44,000 after recording back-to-back runner-up finishes on the Challenge Tour.
The 21-year-old’s hopes of landing a maiden victory on the second-tier circuit were dashed by Joel Sjoholm as the experienced Swede finished strongly to claim the Italian Challenge Open title in Sardinia.
But, having backed up a strong showing the Czech Republic the previous week, Neil is now on course to earn a step up to the European Tour next season, with cards going to the top 15 in the Road to Oman.
“The last couple of weeks have been very encouraging, having displayed the kind of golf I’m capable of,” said the 2014 Amateur champion.
“It obviously puts me in a great position for the rest of the season. I just need to keep up the hard work and the good performances.”
Jimmy Gunn closed with a 66 to finish joint-19th in the Web.com Tour’s Utah Championship, won by American Brice Garnett with a 21-under-par 263 total.
The effort leaves Gunn sitting 21st on the money-list as he battles to secure a PGA Tour spot alongside Russell Knox and Martin Laird.
Welshman Phillip Price overturned a three-shot deficit on the final day to win his first European Senior Tour title at the WINSTONgolf Senior Open.
Price, a member of the winning 2002 Ryder Cup side at The Belfry, started the day three strokes behind American Clark Dennis but claimed the title by a shot after a closing 67.
“I played nice early on and managed to hang on at the end,” said the 50-year-old, who had previously finished second, tied fourth and tied eighth in regular Senior Tour events.
Price’s next appearance will be at the Senior Open Championship on home soil at Royal Porthcawl next week.
Gary Orr tied for 10th, finishing alongside Paul McGinley on seven-under, while defending champion Andrew Oldcorn ended up tied for 19th, just ahead of Ross Drummond and Bill Longmuir.
Defending champions Scotland finished fifth in the European Men’s Team Championship in Austria.
Bidding for a title hat-trick in the event, the Scots beat France 3-2 in their final match at the Diamond Golf Resort.
Spain are the new champions after a narrow 4-3 win over top seeds England in the title decider.
England won the women’s event in Portugal, beating Italy 5.5-1.5 in the final at Montado.
Pauline Rostron, from Formby Ladies and Chester’s Sally Pearson won the R&A Nine Hole Championship Final at Royal Birkdale.
The triumphed with a net 70.5 in an event featuring a group of 42 men and women over the back nine at this week’s Open Championship venue.