Cyanothamnus quadrangulus, commonly known as narrow-leaved boronia,[2] is a plant in the citrus family, Rutaceae and is endemic to eastern Australia.

It is an erect shrub with four-angled branches, bipinnate leaves and white, sometimes pale pink, four-petalled flowers.Cyanothamnus quadrangulus is an erect shrub that grows to a height of 0.3–1 m (1–3 ft) with four-angled, glabrous stems with prominent leaf scars.

[2][3] This species was first formally described in 1863 by Stephan Endlicher from an unpublished manuscript by Allan Cunningham and was given the name Boronia anethifolia.

Endlicher's description was published in Enumeratio plantarum quas in Novae Hollandiae ora austro-occidentali ad fluvium Cygnorum et in sinu Regis Georgii collegit Carolus Liber Baro de Hügel.

[5] This boronia grows in heath and forest and in rocky slopes and ridges between the Border Ranges in Queensland and Wadbilliga Mountain in southern New South Wales.