It has elliptical to egg-shaped leaves that are often greyish green, white flowers about 15 mm (0.59 in) in diameter arranged in consecutive leaf axils and fruit that remain on the plant for some time after maturity.

Flowering occurs from January to February and the fruit is a capsule 4–5 mm (0.16–0.20 in) wide, remains on the plant for some time after maturity and has the sepals attached.

The neotype is "virgate shrubs to 3 m (9.8 ft) high dominating damp sandy heathland" at the western foot of the Strzelecki Peaks on the south-west of Flinders Island in Tasmania.

[8][9] However, Labillardière had confused "Van-Diemen" with "Terre Van-Leuwin", and although he later made the correction on the herbarium sheet in Paris, the name L. sericeum continued to be applied to plants collected in Tasmania.

Leptospermum sericeum is a Western Australian endemic, found near Esperance, which has pink, sessile flowers and does not grow to the height of L.