Cyanothamnus is a genus of flowering plant in the family Rutaceae, native to Australia.

[3] The genus was first described in 1839 by John Lindley in A Sketch of the Vegetation of the Swan River Colony.

A molecular phylogenetic study in 2020 showed that as then circumscribed Boronia was polyphyletic, and Lindley's genus was revived.

[5] A 2021 classification of the family Rutaceae places Cyanothamnus in the subfamily Zanthoxyloideae.

[6] As of September 2021[update], Plants of the World Online accepted the following species:[2]