It is a shrub with elliptic to lance-shaped leaves and groups of 7 to 9 white flowers arranged in leaf axils.

Sannantha crassa is a shrub that typically grows to a height of up to 2.5 m (8 ft 2 in) and has grey, scaly bark.

Flowering has been observed in January and February and the fruit is a bell-shaped to hemispherical capsule 2.5–3.0 mm (0.098–0.118 in) in diameter.

[2][3] This species was first formally described in 1999 by Anthony Bean who gave it the name Babingtonia crassa in the journal Austrobaileya from specimens he collected at Dangars Falls in 1995.

[2][4] In 2007, Peter Gordon Wilson changed the name to Sannantha crassa in Australian Systematic Botany.