Spreading Stenanthemum is a small mat-forming plant with a woody base and slender branches. It has small rounded leaves that are shiny dark green above and slightly hairy underneath. Spreading Stenanthemum has clusters of stalkless white flowers surrounded by brown bracts and two or three very conspicuous whitish floral leaves.
The species is a prostrate undershrub in the Rhamncaeae family, with branches 15-30 cm long. Leaves are obovate, very blunt, about 6 mm long, and the lower surface tomentose. Flowers are about 2 mm in diameter and form small dense, compound terminal heads, with two to three conspicuous floral bracts similar to the foliage leaves but larger and white-tomentose. The outer brown bracts are almost orbicular with two long dorsal awns. The inner bracts are obovate and blunt. The receptacle is hirsute, about 4 mm long, very slender, constricted above the ovary. The upper part often breaks away when the fruit ripens.