Bromus squarrosus is an annual grass, with culms growing 20–60 cm (7.9–23.6 in) high.

The unilateral and lax panicles have few spreading or ascending branches that are erect in youth tend to nod at maturity.

The spikelets are typically solitary, lanceolate in youth and becoming more ovate at maturity, and are 2–4 cm (0.79–1.57 in) long and 5–10 mm (0.20–0.39 in) broad.

The unequal and ovate lemmas have nine faint nerves and broad translucent margins measuring as broad as 1 mm (0.039 in), and the lemmas do not roll inwards at maturity as other Bromus species typically would.

Bromus squarrosus grows in overgrazed pastures, fields, and road verges.