Larkin added a hurling championship medal to his collection in 2004 following a 2–16 to 3–12 defeat of Young Irelands. As scorer-in-chief for the team he finished the game with 0–11, while Young Irelands D. J. Carey, with a personal tally of 3–6, sent a 64th-minute penalty over the bar. Larkin later won his first Leinster medal following a controversial 1–13 to 1–12 defeat of University College Dublin. The subsequent All-Ireland decider on 17 March 2005 pitted James Stephens against Athenry. Larkin scored the first of his nine points after just twenty seconds, to help his side to a 0–19 to 0–14 victory. He finished the championship campaign with a grand total of 3–33, as well as collecting an All-Ireland medal.