Conothamnus trinervis is a plant species in the family Myrtaceae endemic to Western Australia.

It is a shrub with thick, stiff stems, leaves with a sharp point on the tip and heads of usually cream-coloured flowers.

Conothamnus trinervis is an erect or straggly shrub that typically grows to a height of 0.15 to 1.5 metres (0.5 to 4.9 ft) and has thick, stiff branches.

The leaves are usually arranged in opposite pairs, sometimes in whorls of three, 1–4 cm (0.39–1.57 in) long with three veins and a sharp point on the tip.

[2][3] Conothamnus trinervis was first formally described in 1839 by John Lindley who published the description in A Sketch of the Vegetation of the Swan River Colony.