Cyanothamnus occidentalis is an erect, woody shrub that grows to a height of about 1 m (3 ft).

The flowers are white to pale pink and are arranged singly or in groups of up to three in leaf axils on a peduncle 0.5–2 mm (0.02–0.08 in) long.

[2][3] This species was first formally described in 2003 by Marco F. Duretto who gave it the name Boronia occidentalis from a specimen collected in the Wondul Range National Park and the description was published in Muelleria.

[2][4] In a 2013 paper in the journal Taxon, Marco Duretto and others changed the name to Cyanothamnus occidentalis on the basis of cladistic analysis.

[5] The specific epithet (occidentalis) is a Latin word meaning "western",[6] alluding to the fact that in most places, this species has a more westerly distribution than that of other boronias.