Mount Martha is a suburb on the Mornington Peninsula in Melbourne, Victoria, Australia, 50 kilometres (31 mi) south-east of Melbourne's Central Business District, located within the Shire of Mornington Peninsula local government area. Mount Martha recorded a population of 19,746 at the 2021 census.

The Mornington Peninsula is a peninsula located south of Melbourne, Victoria, Australia. It is surrounded by Port Phillip to the west, Western Port to the east and Bass Strait to the south, and is connected to the mainland in the north. Geographically, the peninsula begins its protrusion from the mainland in the area between Pearcedale and an area north of Frankston. The area was originally home to the Mayone-bulluk and Boonwurrung-Balluk clans, and formed part of the Boonwurrung nation's territory prior to European settlement.