The Shire of Diamond Valley was a local government area about 20 kilometres (12 mi) northeast of Melbourne, the state capital of Victoria, Australia.

The name relates to the lowlands to the west of Diamond Creek, a tributary of the Yarra River, which flows through nearby Eltham.

The Diamond Valley can be defined in geographical terms as the area bounded by the Plenty River, the Yarra, the Christmas Hills ridge to the east and the Great Dividing Range to the north.

[3] On 30 September 1964, the North Ward of the City of Heidelberg was severed, and incorporated as the Shire of Diamond Valley.

A small area in the shire's southwest, north of La Trobe University and including the Gresswell Forest Nature Reserve, was transferred to the City of Darebin.