It has rough bark at the base of the trunk, smooth bark above, narrow lance-shaped adult leaves, flower buds in groups of between seven and eleven, creamy white flowers and hemispherical fruit.Eucalyptus mannensis is a mallee, rarely a straggly tree, that typically grows to a height of 2–10 m (6 ft 7 in – 32 ft 10 in) and forms a lignotuber.

[2][3][4][5] Eucalyptus mannensis was first formally described in 1964 by Cliff Boomsma from a specimen collected on Angas Downs Head Station.

[6][7] The specific epithet (mannensis) refers to the Mann Ranges in South Australia.

There are also disjunct populations in the Great Victoria Desert, near Wiluna and near Shark Bay.

Subspecies vespertina is restricted to near-coastal areas between the Murchison River and Shark Bay.