Fimbristylis cinnamometorum is a sedge of the family Cyperaceae that is native to Australia.
The rhizomatous perennial grass-like or herb sedge typically grows to a height of 0.4to and has a tufted habit. It blooms between April and June and produces brown flowers.
In Western Australia it is found in and around swamps, pools along drainage lines and clay-pans and other damp places in the Kimberley region where it grows in loamy soils around sandstone and quartzite.