Grevillea crassifolia is an open shrub that typically grows to a height of. Its leaves are elliptic to oblong, often thick, long and wide with the edges turned down or rolled under, the lower surface densely covered with matted hairs. The flowers are arranged in groups of up to four in leaf axils or on the ends of short side branches and are red, the pistil long with a short style. Flowering occurs from June to December and the fruit is an oval follicle about long.