He scored on his debut for the club, coming on as a substitute on the 65th minute against Watford, in a 2–2 draw at Turf Moor. After scoring on his debut, Manager Eddie Howe praised Treacy's performance. His second later came on 17 September 2011, in a 2–1 loss against Peterborough United. Unfortunately, Treacy suffered a hamstring injury in training that kept him out for two weeks. It wasn’t until on 1 October 2001 when he made his return against Millwall, coming on as a substitute for Marvin Bartley in a 1–0 loss. Since joining Burnley, Treacy became a first team regular for Burnley, playing in the midfield position. He then provided a double assist on 29 November 2011, in a 4–0 win over Ipswich Town. However, Treacy's form and fitness began to falter, resulting him not being in the starting line-up, prompting Manager Howe insisted Treacy remained at the club throughout the transfer window. By the time he was loaned out to Sheffield Wednesday, Treacy went on to make twenty–seven appearances and scoring two times for Burnley at the end of the 2011–12 season.