The Ross Dependency is a region of Antarctica defined by a sector originating at the South Pole, passing along longitudes 160° east to 150° west, and terminating at latitude 60° south. New Zealand's claim to the region was formalized in 1923, when the Governor-General of New Zealand was appointed as the Governor of the Ross Dependency by an Imperial Order in Council made in London, United Kingdom. Since the Antarctic Treaty came into force in 1961, Article 1 of which states "The treaty does not recognize, dispute, nor establish territorial sovereignty claims; no new claims shall be asserted while the treaty is in force", most countries do not recognise territorial claims in Antarctica.

The Dependency takes its name from Sir James Clark Ross, who discovered the Ross Sea, and includes part of Victoria Land, and most of the Ross Ice Shelf. Ross Island, Balleny Islands and the small Scott Island also form part of the Dependency, as does the ice-covered Roosevelt Island.

The scientific bases of Scott Base (New Zealand) and McMurdo Station (USA) are the only permanently occupied human habitations in the area, though Amundsen–Scott South Pole Station is partially within the territory and dependent on logistics operations based in New Zealand. The Dependency has a snow runway at Williams Field, and depending on conditions and time of year, two Ice Runways. This guarantees accessibility by wheeled and ski equipped aircraft year round.