Croydon South was a constituency represented in the House of Commons of the Parliament of the United Kingdom. It elected one Member of Parliament (MP) by the first past the post system. It was created for the 1918 general election when the County Borough of Croydon had grown so the Croydon seat was split into two seats. It did not exist from 1950 to 1955 as an east–west division of the town was chosen instead. Its voters elected twice Labour candidates, for the 1945 and 1966 Parliaments when the Labour Party received strong majorities, and at all other elections elected Conservative candidates.