Cyanothamnus subsessilis is a species of plant in the citrus family, Rutaceae and is endemic to the south-west of Western Australia.

It is a woody, mostly glabrous shrub with simple leaves and flowers with four petals that are white on the front and green to blue on the back.

[2][3] This species was first formally described in 1863 by George Bentham and given the name Boronia subsessilis in Flora Australiensis from a specimen collected by James Drummond.

[4][5] In a 2013 paper in the journal Taxon, Marco Duretto and others changed the name to Cyanothamnus subsessilis on the basis of cladistic analysis.

[2][3] Cyanothamnus subsessilis is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.