Rhynchosia hirta is a vigorously twining or climbing herbaceous, sometimes woody plant, of various sizes, but reaching heights of 2–8 m. Stems are densely covered with short brownish hairs when young. These hairs fall off as the plant matures. Leaves are trifoliolate (with three leaflets), broadly elliptic to ovate, with simple margins, sparsely hairy above, densely covered with reddish brown hairs beneath.

Flowering stalk is occasionally branched, with 7-many flowers. Flowers vary from greenish cream-coloured, to yellow, striped with red; through orange to pink with red or purple venation that sometimes give them a reddish appearance. It flowers from late winter throughout spring to summer (July–March).

The 2-seeded pods (fruit) are narrowly oblong, densely covered in short, velvety grey or rusty-brown hairs. Pods open and twist upon seed maturity, exposing the glossy dark-blue seeds that remain attached to the pods.