The constituency was created for the first election to the Assembly, in 1999, with the name and boundaries of the Meirionnydd Nant Conwy Westminster constituency. It was partly within the preserved county of Clwyd and partly within the preserved county of Gwynedd. The constituency was abolished following boundary changes for the 2007 Assembly elections.
In elections for the National Assembly for Wales, each voter has two votes. The first vote may be used to vote for a candidate to become the Assembly Member for the voter's constituency, elected by the first past the post system. The second vote may be used to vote for a regional closed party list of candidates. Additional member seats are allocated from the lists by the d'Hondt method, with constituency results being taken into account in the allocation.