This Welsh seat on the English border is part of the industrial hinterland north of Wrexham and west of Chester, with large employers including Toyota, BAE and Airbus.^[4] The main population areas in the current seat include Shotton, Connah’s Quay, Buckley, Hawarden and Caergwrle. It was formerly known as East Flintshire until the 1983 boundary review, in which it was renamed after the Alyn and Deeside district created in 1974.

Alyn and Deeside (Welsh: Alun a Glannau Dyfrdwy) is a parliamentary constituency^{[n 1]} represented in the House of Commons of the Parliament of the United Kingdom (at Westminster). The constituency was created in 1983, and it elects one Member of Parliament (MP) by the first-past-the-post method of election.

The Alyn and Deeside Senedd constituency was created with the same boundaries in 1999.

The constituency retained its name and gained wards, as part of the 2023 Periodic Review of Westminster constituencies and under the June 2023 final recommendations of the Boundary Commission for Wales for the 2024 United Kingdom general election.

2024–present: From the 2024 United Kingdom general election the seat of Alyn and Deeside was expanded towards Flint as a result of the abolition of the Delyn constituency in the 2023 Periodic Review of Westminster constituencies. It consists of the Flintshire electoral divisions:

• Aston, Broughton North East, Broughton South, Buckley Bistre East, Buckley Bistre West, Buckley Mountain, Buckley Pentrobin, Caergwrle, Connah’s Quay Central, Connah’s Quay Golftyn, Connah’s Quay South, Connah’s Quay Wepre, Ewloe, Hawarden, Higher Kinnerton, Hope, Llanfynydd, Mancot, Penyffordd, Queensferry, Saltney Mold Junction, Saltney Stonebridge, Sealand, Shotton East, Shotton Higher, Shotton West, Treuddyn, Bagillt East, Bagillt West, Flint Castle, Flint Coleshill, Flint Oakenholt, and Flint Trelawny.