Viana do Castelo is one of the 22 multi-member constituencies of the Assembly of the Republic, the national legislature of Portugal.

The constituency currently elects five of the 230 members of the Assembly of the Republic using the closed party-list proportional representation electoral system.

Viana do Castelo currently elects five of the 230 members of the Assembly of the Republic using the closed party-list proportional representation electoral system.

Results of the 2024 legislative election held on 10 March 2024:[8] The following candidates were elected:[9] José Pedro Aguiar-Branco (AD); Emília Cerqueira (AD); José Costa (PS); Marina Gonçalves (PS); and Eduardo Teixeira (CH).

Results of the 1976 legislative election held on 25 April 1976:[40] The following candidates were elected:[41] Eugénio Anacoreta Correia (CDS); José Rui Fernandes (PPD); Amantino Lemos (PPD); Abreu Lima (CDS); Manuel Tito de Morais (PS); Américo Sequeira (PPD); and Oliveira e Silva (PS).