It has rough, flaky to ribbony bark on the trunk and larger branches, smooth withish bark above, linear to narrow lance-shaped adult leaves, flower buds in groups of seven to eleven, white flowers and barrel-shaped, conical or cup-shaped fruit.Eucalyptus comitae-vallis is a mallee, rarely a tree, that typically grows to a height of 2 to 7 metres (7 to 23 ft) and forms a lignotuber.

[3][5][6] Eucalyptus comitae-vallis was first formally described in 1923 by Joseph Maiden from a specimen collected from Comet Vale by John Thomas Jutson.

[9] In 1934, William Blakely described Eucalyptus brachycorys but the name is considered by the Australian Plant Census to be a synonym.

[2] Comet Vale mallee is mainly found between Menzies and Kalgoorlie in the Mid West, Wheatbelt and Goldfields-Esperance regions of Western Australia where it grows in sandy-clay-loamy soils in open shrubland.

[3][6] This eucalypt is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.