Blyth Valley, formerly known as Blyth, is a constituency^{[n 1]} represented in the House of Commons of the UK Parliament since 2019 by Ian Levy, a Conservative.^{[n 2]}

Further to the completion of the 2023 Periodic Review of Westminster constituencies, the seat will be abolished, with the majority of its contents - excluding the town of Blyth itself - being absorbed into the new constituency of Cramlington and Killingworth, to be first contested at the next general election. Blyth will be included in the new constituency of Blyth and Ashington.^[3]

The constituency is in the former Northumberland Coalfield where mining and shipbuilding were once significant industries. Residents' incomes and wealth are slightly below average for the UK.^[4]

The constituency of Blyth was established under the Representation of the People Act 1948 for the 1950 general election. Following the reorganisation of local authorities resulting from the Local Government Act 1972, it was renamed Blyth Valley for the 1983 general election to correspond with the newly formed Borough of Blyth Valley.

In the 2019 general election, Blyth Valley was the third seat to declare and the first Conservative victory of the election,^[5] pointing towards many similar Conservative victories in Labour's Red Wall^[6] as the night went on.

1950–1974 (Blyth): The Municipal Borough of Blyth, and the Urban Districts of Bedlingtonshire, and Seaton Valley.^[7][8]

Blyth and Bedlington were transferred from Morpeth. Seaton Valley (incorporating Cramlington, Seghill, Earsdon and Seaton Delaval) was added from the abolished constituency of Wansbeck.

1974–1983 (Blyth): The borough of Blyth, and the urban districts of Bedlingtonshire, and Seaton Valley.^[9]

The boundary with Hexham was slightly amended to take account of changes to local government boundaries.

1983–present (Blyth Valley): The Borough of Blyth Valley.^[10][11][12]

Bedlington was transferred to the re-established constituency of Wansbeck. Small area in the south (Backworth and Earsdon), which was now part of the metropolitan borough of North Tyneside in Tyne and Wear, transferred to Wallsend.

• List of parliamentary constituencies in Northumberland
• History of parliamentary constituencies and boundaries in Northumberland