It was originally a parish in Romford Rural District, but the population increased enormously with the building of the London County Council's Becontree Housing Estate and the establishment of the Ford Motor Company's factory.
In 1926 the parish was separated from the rural district as Dagenham Urban District. In 1938 the urban district council successfully petitioned for a charter of incorporation and the area became the Municipal Borough of Dagenham.
In 1965 it became part of the London Borough of Barking (subsequently renamed to Barking and Dagenham).
Some details of archives here 
- Dagenham Charter Record October 1st 1938