[2] The taxonomic validity of this grevillea has been disputed, and many sources treat it as synonymous with G.

[3][4] Grevillea williamsoni is a spreading shrub that grows 0.6–1 m tall.

Leaves are elliptic to narrow, 1.5–4.0 cm long, 3–8 mm wide, entire or (occasionally on adults, commonly on juveniles) with 2–4 spreading triangular teeth; margins shortly and angularly refracted; lower surface subsericeous to subvillous with straight hairs.

[1] Many sources, including the National Herbarium of Victoria and the Australian Plant Census treat G. williamsonii as synononymous with G. aquifolium, with recent studies suggesting it is a sterile variant.

[3][4] The species is known only from a single area in the Grampians Ranges in western Victoria.