The Mornington Peninsula is a peninsula located in the south of Greater 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.
Much of the peninsula has been cleared for agriculture and settlements. However, small areas of the native ecology remain in the peninsula's south and west, some of which is protected by the Mornington Peninsula National Park. In 2002, around 180,000 people lived on the peninsula and in nearby areas, most in the built-up towns on its western shorelines which are sometimes regarded as outlying suburbs of greater Melbourne; there is a seasonal population of around 270,000. On 30 June 2017, the Mornington Peninsula population was recorded at 163,847 people. However, in the peak of summer the population increases to 225,000–250,000 people each year, so that it becomes the most populous coastal holiday area in Victoria, with a larger population than Hobart.