mooney joined shamrock rovers, his first senior club, in 2000, while he was a pupil in coláiste éanna, in dublin. and scored in every round when rovers' won the u17 all ireland title against kingdom boys in 2002. he made his first team debut coming on as a sub against longford town on 6 april 2004. his first goal came on 24 june 2004 against the doomed dublin city. in his fifteen months in the first team he scored nine goals in 40 total appearances.