Early into the 2011–12 A-League season he was deployed as the focal of a midfield diamond, and this contributed to the team's improving form. McBreen scored his first goal of the season in a 3–1 home win over Melbourne Heart, with an 82nd-minute penalty kick, and his only A-League goal scored in normal play came after converting Pedj Bojic's cross in a 3–2 home victory over Adelaide United on 21 January 2012. The Mariners became the A-League Premiers after finishing in first place in the 2011–12 table, also qualifying for the finals series. He appeared as a substitute in the first leg of their 5–2 aggregate defeat to Brisbane Roar in the major semi-final, and as a substitute in the preliminary final against Perth Glory, in which the Mariners were beaten 5–3 in a penalty shoot-out after a 1–1 extra time draw. McBreen made five appearances and scored twice in the 2012 AFC Champions League, as they were eliminated from the tournament after finishing third in their group. He scored 4 goals from 30 matches in 2011–12, and was handed a new contract with the Mariners for the 2012–13 A-League in April.