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 shire covered an area of 74.38 square kilometres (28.72 sq mi), and existed from 1964 until 1994.

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.

Land in the area was first incorporated as part of the Heidelberg Road District on 12 October 1860, which became a shire on 27 March 1864, and was proclaimed as the City of Heidelberg on 11 April 1934. On 30 September 1964, the North Ward of the City of Heidelberg was severed, and incorporated as the Shire of Diamond Valley.

In 1863, the Diamond Reef was discovered by Thomas Wright Soady on Dr John Blakemore Phipps property, which stretched from Reynold's Road to the Diamond Creek.

In 1972, eight years after the Shire of Diamond Valley was established, a Civic Centre was constructed in Greensborough, serving as the headquarters for the local council. That building remained the council's home until 1994.

On 15 December 1994, the Shire of Diamond Valley was abolished; areas south of the Metropolitan Ring Road and the Greensborough Highway merged with the City of Heidelberg, into the newly created City of Banyule, while areas north were merged with parts of the City of Whittlesea and the Shire of Eltham, into the newly created Shire of Nillumbik. 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.

The Diamond Valley Civic Centre in Greensborough is still used by Nillumbik Shire Council.^{[citation needed]}