Bursaria spinosa has a variable habit, and can grow anywhere from 1 to 12 m high. The dark grey bark is furrowed. The smooth branches are sometimes armed with thorns, and the leaves are arranged alternately along the stems or clustered around the nodes and have a pine-like fragrance when bruised. Linear to oval or wedge-shaped (ovate, obovate or cuneate), they are 2–4.3 cm long and 0.3–1.2 cm wide with a rounded apex. The fragrant flowers can occur at any time of year, but mainly appear in the summer. They are arranged in leafy pyramid-shaped panicles.