Located in the southwest corner of Western Australia between Cape Naturaliste and Albany, it is bordered to the north and east by the Jarrah Forest region.

Recognised as a region under the Interim Biogeographic Regionalisation for Australia (IBRA), and as a terrestrial ecoregion by the World Wide Fund for Nature, it was first defined by Ludwig Diels in 1906.

Extending from the ocean to the edge of the Yilgarn craton plateau, for most of its extent it may be adequately approximated as the land within ten kilometres (6 mi) of the coast.

[5] Much of the region is unpopulated, but there are a number of towns with substantial populations, most notably Margaret River, Augusta, Pemberton, Walpole, Denmark and Albany.

The most important plant families are Fabaceae (including the colourful wisteria, Hardenbergia comptoniana), Orchidaceae, Mimosaceae, Myrtaceae and Proteaceae.

Some rainforest relict species do occur, however, such as Anthocercis sylvicola, Albany pitcher plant (Cephalotus follicularis) and wild plum (Podocarpus drouynianus).

[6] The poorer, lateritic soils, about a quarter of the region, are vegetated by medium forest of jarrah (Eucalyptus marginata), which can grow up to 40m tall, and marri (Corymbia calophylla) (up to 60m).

Mammal species include the western ringtail possum (Pseudocheirus occidentalis), chuditch (Dasyurus geoffroii) (particularly found in Jarrah forest), the squirrel-like brush-tailed phascogale (Phascogale tapoatafa), quokka (Setonix brachyurus), yellow-footed antechinus (Antechinus flavipes leucogaster), southern brown bandicoot (Isoodon obesulus), and woylie (Bettongia penicillata ogilbyi).

[6] As with the rest of southwest Australia, in contrast to comparable forest of the south east, there is a low diversity of bird species.

[citation needed] The freshwater streams of the Warren region support only a low diversity of fauna, but much of it is highly endemic.

These contain numerous tourist attractions, most notably the Walpole-Nornalup National Park's Valley of the Giants, which includes a "Tree Top Walk".

[citation needed] The main threat to the biodiversity of the Warren region is the South West's epidemic of dieback, a disease caused by the introduced plant pathogen Phytophthora cinnamomi.

[3] Protected areas include:[3] The Warren region first appeared in Ludwig Diels' 1906 biogeographical regionalisation of Western Australia.

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