The Republican Labour Party was a political party in Northern Ireland. It was founded in 1964, with two MPs at Stormont, Harry Diamond and Gerry Fitt. Each had previously been the sole Northern Ireland representatives of the Socialist Republican Party and the Irish Labour Party and so a common joke was that "two one-man parties had become one two-man party". Fitt won the West Belfast seat in the UK general election of 1966, and held it in the 1970 election.

Fitt left the party and took most of its support with it in August 1970 to found the Social Democratic and Labour Party. The rump party, led by Diamond struggled on for a time but the party was wiped out in the 1973 elections to the Sunningdale assembly.