Newry, Mourne and Down District Council (Irish: Comhairle Ceantair an Iúir, Mhúrn agus an Dúin) is a local authority in Northern Ireland that was established on 1 April 2015. It replaces Down District Council and Newry and Mourne District Council and covers most of the southeast of Northern Ireland. The first elections to the authority were on 22 May 2014. At the 2019 Northern Ireland local elections, Sinn Féin became the largest party with 16 seats. This success was continued at the 2023 Northern Ireland local elections, winning 20 seats.

For the purpose of elections the council is divided into seven district electoral areas (DEA):^[4]

The former Newry & Mourne District Council, uniquely among local authorities in Northern Ireland, had a bilingualism policy which sets out the Council’s commitment to facilitate and encourage the promotion and use of both the Irish language and the English language in the Council area. In order to ensure that the new administrative division does not constitute an obstacle to the promotion of the Irish language, Newry, Mourne and Down District Council was obliged under the terms of Article 7.1 (b) of the European Charter for Regional or Minority Languages, to progressively implement the bilingualism policy throughout the whole of the newly enlarged district.^[5]

The area covered by the new Council has a population of 171,533 residents according to the 2011 Northern Ireland census.^[6]