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."'
Lowry started for Leeds in the Football League Trophy Northern Area Final, second leg game against Carlisle United, in which the game was lost with Lowry missing the decisive penalty in sudden death in the penalty shootout. After the game it appeared as though Lowry was attacked by a set of Carlisle supporters who had invaded the pitch. After starting every game for Leeds Lowry was dropped from the Leeds squad for the match against Brentford after suffering an injury, before returning to Villa when his loan spell ended. On 25 March 2010 Lowry re-signed for Leeds for a second loan spell, with his loan lasting until the end of the season. Lowry started at left back for Leeds against Norwich City on his return to the club, a match Leeds went on to lose 1–0 in injury time. Lowry didn't overley impress the Leeds fans in his loan spell at Leeds, with him being mostly played out of position at Left back for the entire spell, he was substituted for Jonathan Howson in the final game of the season against Bristol Rovers with 1–0 down at the time, but his loan spell ended on a high as Leeds were promoted in 2nd place after scoring two goals to go on and beat Bristol Rovers and secure promotion to The Championship.
THE PLAYERS Championship: A week after collecting his first PGA TOUR victory, nearly became the first player since David Duval (1997) to post first two TOUR victories in back-to-back weeks, finishing T2 at THE PLAYERS, two strokes behind winner Matt Kuchar. Holed a birdie attempt from 21 feet, 7 inches on the par 3 17th in the final round to move to 11-under but couldn't convert a 7-foot, 7-inch birdie on No. 18 that would have given him the clubhouse lead at 12-under. Recorded his fifth career runner-up finish on TOUR in his 73rd start. His T2 performance came in his third start at THE PLAYERS and first in which he made the 36-hole cut. Moved into contention with a 66 in the third round, a career low at TPC Sawgrass. Entered the final round three shots off the 54-hole pace.
PGA Championship: Finished T3 and two strokes behind McIlroy at the PGA Championship in his 20th major championship start, with T19 in 2013 the previous-best finish in four prior PGA Championship starts. Became the first to claim top-five finishes in all four majors since Woods in 2005. Since 1934, is just the third player to perform the feat, joining Woods in 2000 and 2005 and Jack Nicklaus in 1971 and 1973. Played all four majors in 32-under, with McIlroy second on the list, at 27-under.
On July 16, 2017, DeChambeau earned his first PGA Tour victory by winning the John Deere Classic by a single stroke over Patrick Rodgers. He carded a round of 65 in the final round to win his maiden title in his 40th start on tour. The win coming the week before, gained DeChambeau a place in the 2017 Open Championship, where he missed the cut after rounds of 76–77 (+13).