Phebalium longifolium is a shrub that typically grows to a height of 3 m (9.8 ft).

It is more or less covered with silvery to rust-coloured scales except for the upper surface of the leaves and the front of the petals.

The petals are elliptical, about 3 mm (0.12 in) long and densely covered with scales on the back.

[2][3] Phebalium longifolium was first formally described in 1959 by Stanley Thatcher Blake in Proceedings of the Royal Society of Queensland from specimens he collected near Wallaman Falls in 1951.

[2][3] This phebalium is classified as "least concern" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999.