)[2] It is a distinctive shrub with stiff branches, silvery new growth, prickly leaves and spikes of purple flowers in late spring.

Melaleuca williamsii is a shrub growing to 2.5 m (8 ft) tall with rigid branches and new growth covered with soft, silky hairs giving a silvery appearance.

[3][4][5][6] Melaleuca williamsii was first named in 2009 by Lyndley Craven in Novon when Callistemon pungens was transferred to the present genus.

[7][8] It had previously been known as Callistemon pungens, first formally described by Roger Spencer and Peter Lumley in 1990 in Muelleria, based on plant material collected from near Hillgrove.

[9] The specific epithet (williamsii) honours John Beaumont Williams, a botanist who was expert in the flora of the Northern Tablelands region of New South Wales.