It is a plain punctuated by granite and quartz outcrops and ranges, with a semi-arid Mediterranean climate and vegetation consisting mostly of mallee-heath and proteaceous scrub.

Recognised as a bioregion under the Interim Biogeographic Regionalisation for Australia (IBRA), it was first defined by John Stanley Beard in 1980.

It has an area of about 29,000 square kilometres (11,000 sq mi), making it about 9% of the South West Province, 1% of the state, and 0.3% of Australia.

The region's topography consists of a plain that rises from near sea level to an altitude of about 200 metres (660 ft), broken in places by outcrops of granite domes and quartzite ranges.

The remaining 13% of the region falls within the "Extensive Land-use Zone", where the native vegetation has not been cleared but may have been degraded by the grazing of introduced animals and/or changes to the fire regime.

[3] More than half of the remaining vegetation is now in protected areas, such as the Fitzgerald River National Park and the Nuytsland Nature Reserve.

Recognition of the Esperance Plains as a distinct biogeographical region appears to have been due to Edward de Courcy Clarke.

In 1980, John Stanley Beard published a phytogeographical regionalisation of the state based on data from the Vegetation Survey of Western Australia.