Sussex Land District is a land district (cadastral division) of Western Australia, located within the South-West Land Division on the state's west coast. It covers the south-western corner of the state and includes the townsites of Busselton, Margaret River and Augusta as well as Cape Naturaliste and Cape Leeuwin.^[1]

The system of land districts came together in an ad-hoc fashion, and the Sussex district started to be subdivided in 1840 well before any thought was given to formally defining its boundaries.^[2] The definition later used by the Lands and Surveys department came from an 1862 gazettal which read as follows:^[3]

Bounded on the North by an East line from the sea-coast to Capel River through the North end of Wonnerup Inlet, then by said river upwards to location 171 (exclusive), then by a South-easterly line to junction of Padbury Brook with the River Blackwood; on the West and South by the sea-coast; and on the East by the Blackwood downwards to its junction with a South line through Black Point, thence by that line to the sea-coast.