Elections to Newry and Mourne District Council were held on 18 May 1977 on the same day as the other Northern Irish local government elections.

The election used six district electoral areas to elect a total of 30 councillors.

Note: "Votes" are the first preference votes.

1973: 3 x UUP, 2 x SDLP, 1 x Independent Nationalist 1977: 2 x UUP, 2 x SDLP, 1 x DUP 1973-1977 Change: SDLP and DUP gain from UUP and Independent Nationalist 1973: 2 x SDLP, 1 x Alliance, 1 x Independent Nationalist 1977: 2 x SDLP, 1 x Alliance, 1 x Independent Nationalist 1973-1977 Change: No change 1973: 2 x SDLP, 2 x Independent Unionist 1977: 2 x SDLP, 2 x UUP 1973-1977 Change: UUP (two seats) gain from Independent Unionist (two seats) 1973: 3 x SDLP, 2 x Independent Unionist, 1 x Alliance, 1 x Republican Clubs 1977: 3 x SDLP, 2 x UUP, 1 x Alliance, 1 x Independent Nationalist 1973-1977 Change: UUP (two seats) and Independent Nationalist gain from Independent Unionist (two seats) and Republican Clubs 1973: 3 x SDLP, 1 x Republican Clubs, 1 x Independent Republican, 1 x Independent Unionist 1977: 4 x SDLP, 1 x Independent Nationalist, 1 x Independent Republican 1973-1977 Change: SDLP (two seats) gain from Republican Clubs and Independent Unionist, Independent Nationalist leaves SDLP 1973: 2 x SDLP, 2 x Alliance 1977: 2 x SDLP, 1 x Alliance, 1 x UUP 1973-1977 Change: UUP gain from Alliance