Argyrolobium rupestre is a low-growing perennial, with a woody taproot, with stems up to 400 mm long, that may look like a ground cover at times. Stems appressed, numerous, shortly erected, slender and covered with short, soft, golden-brown or greyish hairs, mostly less than 1 mm in diameter, up to 2.5 mm in diameter at the base. Stalks much longer than the leaves.

Leaves usually well-spaced, trifoliate, with leaflets elliptic-lanceolate to obovate-elliptic, sparsely pilose to silky hairy on both surfaces; petiole 4–20 mm long.

Inflorescence leaf-opposed, pedunculated, racemose, terminal, 1–5-flowered. Flowers are bright yellow, often becoming brownish orange with age, densely hairy on the outside. The base of the flower becomes hairy while the ovary is still developing. Fruit a pod 18–40 mm long, flat, sparsely pilose to densely pubescent, 8–14-seeded. They split open when mature and each half twists in a spiral, releasing the seeds, which are 1.5–2.0 mm long, compressed, dark brown. Flowers in spring to late summer (September to February).