Eucalyptus ultima is a species of mallee that is endemic to a small area in the Gascoyne region of Western Australia.

[2][3][4] Eucalyptus ultima was first formally described in 1999 by Lawrie Johnson and Ken Hill in the journal Telopea from specimens collected by Ian Brooker in the Shothole Canyon in the Cape Range National Park in 1977.

[3][5] The specific epithet (ultima) is from the Latin ultimus meaning "farthest" or "most distant", referring to its occurrence compared to related eucalypts.

[3] This mallee is only known from rocky rises in the Cape Range National Park, where it grows in skeletal soils over limestone.

[3][4] This eucalypt is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.