John Dinneen (23 March 1867 – 1 January 1942) was an Irish Farmers' Party politician. A farmer by profession, he was first elected to Dáil Éireann at the 1922 general election as a Farmers' Party Teachta Dála (TD) for the Cork East and North East constituency. He was re-elected at the 1923 general election for the Cork East constituency. He lost his seat at the June 1927 general election.
His nephew Liam Ahern served as a Fianna Fáil Senator and TD from 1957–74 and his grand-nephew Michael Ahern, son of Liam Ahern, has been a Fianna Fáil TD for Cork East since 1982.