Grevillea costata is a spreading shrub that typically grows to a height of 0.8–1.5 m (2 ft 7 in – 4 ft 11 in) and has many ridged, silky-hairy branchlets. Its leaves are linear, 15–45 mm (0.59–1.77 in) long and 0.8–1.3 mm (0.031–0.051 in) wide with the edges rolled under, enclosing all but the mid-vein. The flowers are arranged in groups of four to ten in leaf axils or on the ends of branchlets and are white, the pistil 7.0–9.5 mm (0.28–0.37 in) long with a white to cream-coloured, sometimes pink style. Flowering occurs from May to September and the fruit is an elliptic to oblong follicle 9.5–11 mm (0.37–0.43 in) long with prominent ridges.^[3][4][5]

Grevillea costata was first formally described in 1974 by Alex George in the journal Nuytsia from specimens collected by Charles Gardner near rocks in the Murchison River in 1931.^[5][6] The specific epithet (costata) means "ribbed", referring to the fruit.^[5][7]

This grevillea grows in sand and among rocks in the river bed of the Murchison River in the Carnarvon, Geraldton Sandplains and Yalgoo biogeographic region of Western Australia.^[3][4]

Grevillea costata is listed as Least Concern on the IUCN Red List of Threatened Species. Although its estimated extent of occurrence is relatively small at 6000km², its population is stable and faces no known major threats. Most of this species' range occurs in the protected area of Kalbarri National Park.^[1]

It is also listed as "Priority Three" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions,^[4] meaning that it is poorly known and known from only a few locations but is not under imminent threat.^[8]

• List of Grevillea species