The poison star-apple is a shrub or tree, normally 2-3 m high, but can grow up to 13 m in some instances. It is single or multi-stemmed with branches that grow straight up, forming a dense canopy.

The bark is grey to brown, and rather smooth or sometimes wrinkled. The young branches and the new growth are covered in soft, yellowish to pale brownish, velvety hairs. The leaves are simple and arranged alternately or spirally. They are narrowly oblong, egg-shaped or oval with bluntly pointed or rounded tips, the base of the leaf narrowing, are glossy, leathery, dark green and hairless above and pale green and sparsely to densely covered with hairs below. The margin is often tightly rolled under, entire and not wavy. The central vein is raised below.

The flowers are borne singly, on long, lax, leaf stalks, are bell-shaped, drooping and creamy white and can be seen from November to March. The 5-lobed calyx and petals curl backwards. The male and female flowers are on separate plants.

The fruit appears from March to October and is an almost round, slightly flattened berry with dense orange-yellow, velvety hairs. The persistent calyx has 5 narrow lobes that usually curve backwards.

There are 3-8 dark, shiny brown seeds.