Cetraria australiensis is a species of saxicolous (rock-dwelling), fruticose lichen in the family Parmeliaceae.

[3] Cetraria australiensis features a fruticose (shrub-like) thallus that is decumbent, meaning it lies flat but may rise slightly.

The lobes comprising the thallus are flattened and can be up to 2 mm wide, often plane or slightly grooved (canaliculate), and are richly branched in a forked (dichotomous) manner, creating an entangled appearance.

[4] In terms of chemistry, Cetraria australiensis contains lichesterinic and protolichensterinic acids, with all standard spot tests returning negative results.

It typically forms extensive, loose mats on the ground within heathland and bolster moor habitats, often intermixed with species of Cladia and Cladonia.