Eucalyptus cyclostoma is a species of mallee that is endemic to an area in the south of Western Australia.

It has whitish-grey-cream, brown and pinkish grey coloured bark that is flaky to ribbony can be rough or smooth.

Mature buds are cylindrical to pear-shaped with a beaked operculum with inflexed stamens and oblong anthers.

[2][4] The species was first formally described by the botanist Ian Brooker in 1981 in the journal Brunonia from a specimen he collected west of Balladonia in 1970.

[2] Eucalyptus cyclostoma is part of the subgenus Symphyomyrtus section Dumaria in a sub-group of nine closely related species in the series Ovulares.