He made his debut for the club two days later, coming on as a substitute for Jermaine Johnson in the 78th minute, in a 1–0 win over Leyton Orient. After making appearance, mostly from coming on the bench, Treacy scored his first Sheffield Wednesday goal, coming from a direct free kick and provided a winning goal, in a 2–1 win over Brentford on 28 April 2012. His contributions at the club saw the "Owls"' promotion back to the Championship during the 2011–12 season. After scoring once in seven appearance, Treacy hinted he could turn his loan move from the club into a permanent basis. However, Sheffield Wednesday wasn't keen on signing him on a permanent basis and returned to his parent club.