Crassula subulata is a succulent shrublet that grows to 50 cm when the inflorescence is present. Branching at the base, the plant grows many leafy stems that are red and erect. The leaves are opposite, smooth, 1,5 cm long and narrow, but sometimes up to 5 mm wide. Leaf pairs are fused at the base and broad, tapering to their upturned tips. There margins are angular, the lower leaf surface convex, the upper one flat. Short recurving whitish hairs occur in two bands along the young stems below the points where the leaf-pairs join.
Creamy white flowers grow in densely branched and flat-topped clusters at stem tips. Each flower is about 5 mm long. Flowering happens from midspring to early summer.
The species grows from Vanrhynsdorp in the Western Cape to Port Elizabeth in the Eastern Cape on semi-arid rocky slopes. This plant was flowering in October south of Barrydale (Vlok and Schutte-Vlok, 2010; Bond and Goldblatt, 1984; iSpot).