It usually has smooth, pinkish grey bark, lance-shaped to curved adult leaves, flower buds in groups of three or seven and conical or hemispherical fruit with the valves protruding.Eucalyptus flindersii is a mallee, rarely a small tree, and typically grows to a height of 1–5 m (3 ft 3 in – 16 ft 5 in) and usually has smooth, dull, grey bark that sheds in flakes to reveal a paler layer, sometimes with rough bark at the base of the trunk.

Young plants and coppice regrowth have stems that are more or less square in cross-section, and leaves that are petiolate, egg-shaped, 45–110 mm (1.8–4.3 in) long and 25–70 mm (0.98–2.76 in) wide.

The flower buds are arranged in leaf axils in groups of three or seven on an unbranched peduncle 4–18 mm (0.16–0.71 in) long, the individual buds sessile or on pedicels up to 5 mm (0.20 in) long.

[2][3][4][5][6] Eucalyptus flindersii was first formally described in 1980 by Clifford Boomsma in the Journal of the Adelaide Botanic Gardens from a specimen collected by Roger Callen on Mount Hack in the Flinders Ranges.

[4] The South Australian grey mallee grows on slopes and between rocks in open woodland, mainly in the Flinders Ranges but with outliers to the south near Yunta and Quorn.