Blyth Valley is a borough and district in south-east Northumberland, England, bordering the North Sea and Tyne and Wear. The two principle towns are Blyth and Cramlington. Other centres include Seaton Delaval, and Sleaton Sluice.
The borough was formed on April 1, 1974 by the merger of the borough of Blyth, Seaton Valley urban district, and part of the borough of Whitley Bay.