Delyn is a constituency of the Senedd. It elects one Member of the Senedd by the first past the post method of election. Also, however, it is one of nine constituencies in the North Wales electoral region, which elects four additional members, in addition to nine constituency members, to produce a degree of proportional representation for the region as a whole.

The constituency was created for the first election to the Assembly, in 1999, with the name and boundaries of the Delyn Westminster constituency. It is entirely within the preserved county of Clwyd.

As created in 1999, the North Wales region included the constituencies of Alyn and Deeside, Caernarfon, Clwyd West, Clwyd South, Conwy, Delyn, Vale of Clwyd, Wrexham and Ynys Môn. For the 2007 election the region included Aberconwy, Alyn and Deeside, Arfon, Clwyd South, Clwyd West, Delyn, Vale of Clwyd, Wrexham and Ynys Môn.

In elections for the Senedd, each voter has two votes. The first vote is for a candidate for the voter's constituency, elected by the first past the post system. The second vote is 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.

• North Wales (Senedd electoral region)
• Senedd constituencies and electoral regions