The council was formed in 1973 under the Local Government Act (Northern Ireland) 1972. Its area was formed from Kilkeel, Newry and Warrenpoint Urban Districts and Kilkeel and Newry No. 1 Rural Districts in County Down, and from Newry No. 2 Rural District in County Armagh. From 1973 to 1985, the council area consisted of six electoral areas. In 1985, this was reduced to five electoral areas: Crotlieve, Fews, Newry Town, Slieve Gullion and The Mournes. One of its 30 wards, Rathfriland, was transferred to Banbridge Council in 1993. At the elections of 2005, 30 members were elected from the following political parties: 14 Sinn Féin, 9 Social Democratic and Labour Party (SDLP), 3 Ulster Unionist Party (UUP), 1 Democratic Unionist Party (DUP), 2 Independents and 1 United Kingdom Independence Party (UKIP).