	Carroll was given the 3 shirt by newly appointed manager Liam Buckley when he signed a new two-year contract to keep him at the club until the end of the 2013 season, on 18 December 2011. Carroll started in all of the Saints pre-season games and featured at a new attacking position of left wing as well as his familiar left back role. He provided the assist for Chris Forrester's wonder goal against Phoenix in a 4–0 win in the Leinster Senior Cup at Richmond Park. He played in yet another new role for the team when he played as a center midfielder against U.C.D in the EA Sports Cup having previously played there for his NUI Maynooth college team. Carroll impressed in his sides Leinster Senior Cup Quarter Final defeat away to Shamrock Rovers at Tallaght Stadium. This earned him his first league appearance of the season at home to Cork City and played well, putting in some very good crosses and nearly scoring. It was a sense of Dé-ja-vu for Carroll when Pats once again played Crumlin United in the FAI Cup Second Round. Just like the previous season, the Saints won 3–0 with Carroll scoring and getting the FAI Ford Man of the Match award, this time for his excellent play at centre midfield and his cool finish after 12 minutes. Carroll's first start in a Dublin derby in the league came within the three derby he played in in the space of seven days, when he started at centre-midfield vs Bohemians in a 2–1 win. The other two games included the 120 minutes of the EA Sports Cup Quarter-final vs. Shamrock Rovers where he started at his familiar left back role, and the third was when he came on at half time for Christy Forrester at half time in the 1–0 win over Northside rivals Shelbourne. Carroll played three times in the Saints 2012 Europa League, the first was away to Íþróttabandalag Vestmannaeyja at the Hásteinsvöllur in Iceland when he played a big part in getting Pats through after extra-time, holding the ball up and protecting the back four. The other two were against German giants Hannover 96, one at the Tallaght Stadium and the other in front of 25,000 at the AWD-Arena. Carroll scored his first ever League of Ireland goal when he scored the winner in a 2–1 Dublin derby win over Shamrock Rovers on 25 September 2012. Carroll started the 2012 FAI Cup Final against Derry City on 4 November at the Aviva Stadium but was substituted off early in the game due to injury as the Saints agonisingly lost 3–2 in extra-time.