Erect or spreading shrub, 0.5–1.5 m tall, non-sprouting. Branchlets sparsely to densely appressed-pubescent at flowering, sometimes patchily glabrescent. Leaves usually subterete, thick, slightly to markedly compressed-pentagonal to -heptagonal in cross-section, shallowly grooved longitudinally, 2–9 (–12.5) cm long, 1–2 mm diam., glabrous; longitudinal veins 6 or 7 all around (2 marginal, 3 below and 1 or 2 above), alternating with grooves. Leaves rarely flat or concave, linear to very narrowly obovate, 2–6 mm wide, with prominent marginal veins and longitudinal veins 3 below, 1 above (sometimes upper vein obscure).

Inflorescence a solitary axillary umbelliform raceme, with 8–14 flowers; pedicels cream-white, glabrous. Perianth cream-white. Pistil 5–9.5 mm long; gland subglobular, ±compressed, 0.2 mm high.

Fruit 1–3 per axil, scarcely woody, sessile, obliquely ovate-acuminate (almost straight abaxially), usually slightly recurved, 0.6–0.8 cm long, 0.3–0.35 cm wide, scarcely beaked but with prominent readily broken apiculum. Seed ±elliptic-rhombic, 4.8–5.5 mm long, very shortly winged; wing extending very narrowly down both sides and around base of body, sometimes notched, dark blackish brown.

Hakea sulcata is moderately uniform in leaf morphology throughout its range, having narrow 5–7-angled leaves, but unusually broad-leaved populations occur in the Scott R. district east of Augusta and in the vicinity of the Hay R., east of Denmark.

Hakea gilbertii is similar to H. sulcata but differs in its much larger fruit, slightly more slender leaves with exceptionally long-acuminate needle-sharp mucro, elongate racemes and paler seeds with a much larger wing.

 The name H. sulcata has been widely misapplied to related species with terete furrowed leaves, notably H. invaginata and H. scoparia when these species have been grown as ornamentals. Hakea sulcata is quite distinct, especially in its inconspicuous tiny fruit, the smallest in the genus.