Boronia crenulata is a shrub which grows to a height of about 0.25–1.2 m (0.8–4 ft) and has weak, thin stems which often trail between other plants. The leaves are variable in shape, sometimes even on one plant, but in general are about 20 mm (0.8 in) long and 2 mm (0.08 in) wide, strap-like or egg-shaped with the narrower end towards the base. There are usually a few long soft hairs on the leaves and the margins of the leaves usually have a few small teeth. The flowers are pink to reddish and are scattered singly or in small groups in leaf axils or at the ends of the stems. The flowers are about 1 cm (0.4 in) in diameter on a stalk 4 mm (0.2 in) long. The sepals are egg-shaped to triangular, 1.5–2 mm (0.06–0.08 in) long and usually have a sharp, pointed tip. There are four glabrous petals and eight stamens.