Cyathochaeta avenacea is a sedge of the family Cyperaceae that is native to Australia.
The monoecious and rhizomatous perennial sedge with a tufted habit that typically grows to a height of 0.4to and to about 11NaN1 wide. The plant blooms between November and March producing brown flowers.
In Western Australia it is found along the coast in peaty-swampy areas along the coast of the Wheatbelt, Peel, South West, Great Southern and Goldfields-Esperance regions where it grows in lateritic loam to sandy soils.