In 2009, McCarthy was elected to Cork County Council for the Fermoy area as a Labour Party candidate.[4] He was re-elected as a Labour councillor in 2014.[1] He left Labour in October 2015, when he was not allowed seek a nomination in Cork East for Labour at the 2016 general election, having being previously denied a nomination at the 2011 general election.[5] He joined Fine Gael in November 2015,[6] and stood as a Fine Gael candidate at the 2016 general election but was not elected. He was re-elected to Cork County Council in 2019 as a Fine Gael councillor.
A small business owner, McCarthy runs an off-licence in Fermoy.[1]