The Honda Classic: After beginning the final round of The Honda Classic with a four-stroke lead, posted a 1-over 71 to win by the same margin for his fourth career PGA TOUR title. It marked the first of five 54-hole leads he converted to victory. Opened with back-to-back 66s for the second consecutive year and posted a 65 in the third round to post the best 54-hole total since the event moved to PGA National in 2007 at 13-under 197. Seized the 54-hole lead with the widest margin of his career entering a final round. Turned in 2-over 37, but posted three birdies on the back nine to take command of the tournament. Despite bogeys on the 71st and 72nd holes, claimed his first victory since the 2015 Dell Technologies Championship. Finished the week second in Strokes Gained: Putting (7.392) and moved to 10th in the FedExCup standings and ninth in the Official World Golf Ranking, his first time in the top 10 since the 2016 BMW Championship.
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.
On August 26, 2018, he won The Northern Trust for his first playoff victory; in the process, he established a new record for the tournament when held at the Ridgewood Country Club, with a score of 266, besting the old Ridgewood record of 270, which was set in 2014 by Hunter Mahan. The following week, he won at the Dell Technologies Championship played at TPC Boston in Norton, Massachusetts, with a final score of −16, two shots clear of Justin Rose. This put him over 2000 points ahead of the second place player, Dustin Johnson, in the FedEx Cup rankings. This margin secured him top seeding at The Tour Championship, regardless of his finish at the BMW Championship. This also marked his fourth win on tour, third for the year, and second during the playoffs. At the Tour Championship, DeChambeau finished 19th out of 30 participants. As a result, he fell to 3rd in the FedEx Cup, winning $2,000,000.
Lowry made his Leyton Orient debut, playing as a left-back position, in the opening game of the season, which saw Leyton Orient lost 2–1 to Chesterfield. Since his debut, Lowry established himself in the left-back position in the first half of the season despite being sidelined with suspension and fitness concern that saw him out for two matches. Following his return to the first team, Lowry played in the central-defense between December and March until he dropped from the first team throughout March. Lowry went on to make his first team return throughout 2014–15 season, making thirty-four appearance in his first season at Leyton Orient.
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.
Enjoyed a stellar rookie season, with seven top-10 finishes and a 32nd-place finish in the FedExCup standings that led to him winning PGA TOUR Rookie of the Year honors. Finished inside the top 30 on the money list to qualify for the Masters and the U.S. Open. Played in first three Playoff events, slipping from 21st to 32nd and out of the TOUR Championship.
Frys.com Open: At the Frys.com Open in Scottsdale, Ariz., reached a three-way playoff with Jamie Lovemark and eventual-winner Troy Matteson. Began the final round four strokes behind Matteson, but played his first five holes in 5-under, punctuated by a hole-in-one from 211 yards at the par-3 fifth hole. After finishing T2 in the playoff, he had recorded all eight of his professional rounds in the 60s. Thanks to the T7 in Las Vegas at the Justin Timberlake Shriners Hospitals for Children Open and T2 finish at Grayhawk GC, he surpassed No. 150 from the 2008 money list, earning special temporary membership on TOUR for the remainder of the season.
On 27 January 2016, Lowry returned to Australia after a decade away from Australia when he signed a two-and-a-half-year deal with A-League side Perth Glory. Upon joining Perth Glory, Lowry said of the move, quoting: "I've got a lot of experience behind me now and I want to use it to guide the young lads who are in this young squad. I've spent 11 years in England and it's shaped my football over there and I'm really happy to be here and get stuck into the games"