It has rough, fibrous bark on the trunk and branches, lance-shaped to curved adult leaves, flower buds in groups of eleven to twenty five, white flowers and cup-shaped or hemispherical fruit.

Eucalyptus willisii is a tree or a mallee that typically grows to a height of 10 m (33 ft) and forms a lignotuber.

The flower buds are arranged in leaf axils in groups of eleven to twenty five on an unbranched peduncle 2–8 mm (0.079–0.315 in) long, the individual buds on pedicels 2–4 mm (0.079–0.157 in) long.

[3][4][5] Eucalyptus willisii was first formally described in 1983 by Pauline Ladiges, Chris Humphries and Ian Brooker in the Australian Journal of Botany from specimens collected near Mount Oberon in Wilsons Promontory National Park in 1982.

[4][7] The shining peppermint is endemic to Victoria from Cranbourne to around Bairnsdale in the west, and south to Wilsons Promontory[2] where it is found growing in sandy areas or on granite hills in scrubland communities.