Lowry was the 2007 Irish Amateur Close Champion, defeating Niall Turner 4 & 3 in the final. While still an amateur in May 2009, he won The Irish Open on the European Tour, defeating Robert Rock on the third hole of a sudden death playoff. The win, on his tour début, made him just the third amateur to win on the European Tour, following Danny Lee earlier in the 2009 season, and Pablo Martín in 2007. Lowry shot a 62 to equal the lowest ever by an amateur on the circuit and led from the second round onwards.
Born in Modesto, California, to John Howard Aldrich DeChambeau and Janet Louise Druffel, DeChambeau moved to Clovis, east of Fresno, at age seven. He attended Clovis East High School and won the California State Junior Championship at age 16 in 2010. DeChambeau graduated in 2012 and accepted a scholarship to Southern Methodist University in Dallas, Texas, majoring in physics.
All of DeChambeau's irons and wedges are cut to exactly the same length: 37.5 inches (95.3 cm). Their lie and bounce angle are also the same; only the lofts are different. In addition to the single-length concept, his clubs are unusual for their extremely upright lie angle.  DeChambeau keeps the club on the same plane throughout his swing and does not turn his wrists during his swing. In 2011, at the suggestion of his instructor Mike Schy, DeChambeau switched to JumboMax Grips, the largest grips commercially available. The larger grips allow DeChambeau to hold the grips in his palms and not his fingers.
BMW Championship: Entered the BMW Championship No. 36 in the FedExCup standings, with his T39 finish at Conway Farms outside Chicago leading to a final ranking of No. 38. Advanced to the TOUR Championship by Coca-Cola in 2012 (finished No. 28 in the FedExCup), but other three seasons led to near misses of cracking the top 30 in the FedExCup (No. 43 in 2011 and No. 32 in 2010).
THE PLAYERS Championship: After beginning the final round of THE PLAYERS Championship three strokes off the lead, at 7-under 209, played his last six holes in 6-under to post a 6-under 66 and join a three-hole aggregate playoff with 2008 PLAYERS champion Sergio Garcia and Kevin Kisner. Finished birdie-par-birdie-eagle-birdie-birdie on Nos. 13-18 in regulation. Played Nos. 15-18 in a 5-under total of 11 strokes. The four-hole score of 11 set a new single-round low for the final four holes at TPC Sawgrass. Previously, seven players had finished with a score of 12 on the final four holes. When Garcia was eliminated after the aggregate playoff, Fowler and Kisner returned to the famed, par-3 17th for sudden death. Fowler converted a 4-foot, 8-inch putt for birdie to claim the title. Before his back-nine charge, his mother had made her way to the airport to leave town. A text message alerting her to her son's rally resulted in her immediate return to TPC Sawgrass in time to witness the win. With the victory, moved to ninth in the Official World Golf Ranking and No. 7 in The Presidents Cup standings.
After a T-12 finish at the Masters, Fowler earned his first win in over three years with a playoff victory at The Players Championship in May. Trailing Sergio García midway through the final round by five shots, Fowler played the final six holes in 6-under par, including an eagle at the par-5 16th. After a birdie at the famous 17th hole, Fowler's final birdie of the round on 18 left him at 12-under par. Both García and Kevin Kisner had birdie attempts to win at the 18th in regulation, but both missed and the three men went to a three-hole aggregate playoff to decide a winner on holes 16–18. Fowler and Kisner went par-birdie-par to tie at −1 while García's three pars left him at even and he was eliminated. Thus Fowler and Kisner went to sudden death starting at the 17th, where Kisner's tee shot landed within about 12 feet (3.7 m) of the cup. Fowler answered with a shot inside of five feet, and when Kisner's birdie attempt slid by, Fowler responded by making his short birdie to claim the championship. Fowler played his final 10 holes in 8-under par. On July 12, he won the Aberdeen Asset Management Scottish Open on the European Tour, shooting a 12-under-par 268. On September 7, he won the Deutsche Bank Championship, the second FedEx Cup Playoffs event, by one stroke over Henrik Stenson, for his third victory on the PGA Tour.
Fowler is one of four golfers in the "Golf Boys" group along with fellow PGA Tour players Ben Crane, Bubba Watson and Hunter Mahan. The Golf Boys released a YouTube video of the song "Oh Oh Oh" on the eve of the 2011 U.S. Open. Farmers Insurance is donating $1,000 for every 100,000 views of the video. The charitable proceeds will support both Farmers and Ben Crane charitable initiatives.
On 23 November 2011, Lowry was again loaned out to play in the Championship, this time to Millwall until 3 January 2012. He followed Aston Villa team-mate Nathan Baker who also signed on loan for Millwall two days earlier. Lowry made his Millwall debut three days later, where he played 90 minutes, in a 0–0 draw against Crystal Palace. His impressive display at Millwall soon earned a loan extension. Weeks later on 13 January 2012, Lowry was sent-off in the 22nd minutes after stamping on Nikola Žigić, which saw Millwall lose 6–0. Three years on after signing for Birmingham City, Lowry stated, quoting: "Whatever club I play for I fully commit to that club at the time. I play with my heart on my sleeve. Sometimes in the past I have gone overboard but I was a younger player then, I have learned a lot from these types of experiences. But I am an aggressive player, that’s the way I like to play and I can’t change the way I play. I will use my experience now and be a bit more clever."'
At the 2016 U.S. Open at Oakmont Country Club near Pittsburgh, Lowry shot 65 (−5) in the third round for 203 (−7) and a four-stroke advantage over Dustin Johnson and Andrew Landry at the 54-hole stage. The 65 was Lowry's joint career best round at a major championship. Due to weather delays on Thursday, the third round was not completed until early on Sunday, and Lowry birdied two of his remaining four holes to extend his two stroke overnight lead to four. In the final round he was in contention for the title, within one shot of Dustin Johnson after 12 holes, before three consecutive bogeys on holes 14, 15 and 16 ended his chances. He finished the tournament tied for second place, with a final round score of 76.
Waste Management Phoenix Open: Won fifth PGA TOUR title at the Waste Management Phoenix Open in his 220th career start at the age of 30 years, 1 month, 21 days. Began the final round with a four-shot lead and won by two strokes after recording a double bogey and triple bogey en route to a closing 3-over 74. Became the first player since 1983 to win with both a double bogey and triple bogey or worse in the final round. Triple bogey came at No. 11 at TPC Scottsdale after he chipped his ball into the water and received an additional penalty when the ball rolled back into the water after he had placed it back into play. Marked the second time of seven occasions he converted a 54-hole lead to victory.
Lowry made his professional debut in the 2009–10 UEFA Europa League in an away fixture at Rapid Vienna. On 17 September 2009, Lowry signed a three-month loan deal with Football League Championship side Plymouth Argyle. Lowry made his Plymouth Argyle debut on 19 September 2009, playing 90 minutes, in a 3–1 loss against Newcastle United. He played 13 league games for Plymouth during his loan spell, where he impressed many and was recalled by Villa who required Lowry's services as cover after some injuries to defenders.