Three years later in 1962 Larkin made his senior competitive debut in a National Hurling League game against Tipperary. He was later included on Kilkenny's championship panel and won his first Leinster medal following a 2–10 to 0–9 defeat of Dublin. This victory allowed Kilkenny to advance directly into an All-Ireland showdown with Waterford on 1 September 1963. "The Cats" entered the game as underdogs, however, ace marksman Eddie Keher proved to be the difference with a magnificent display in which he scored fourteen points. Despite a hat-trick of goals from Waterford's Séamus Power, Kilkenny secured a 4–17 to 6–8 victory. It was Larkin's first All-Ireland medal.