Walsh made his championship debut with Kilkenny in 1904. He won his first Leinster medal that year as Kilkenny recorded a 2-8 to 2-6 defeat of Dublin in the provincial decider. The subsequent All-Ireland final was delayed until 24 June 1906, with three-in-a-row hopefuls Cork providing the opposition. It was the beginning of a hugely successful era for "the Cats" as Cork were heading into decline. A first half goal by Dick Doyle put Kilkenny in the driving seat, while goalkeeper Pat "Fox" Maher made a great save in the dying moments of the game to help Kilkenny to a 1-9 to 1-8 victory. It was Walsh's and Kilkenny's first All-Ireland triumph.