Prasophyllum unicum is a species of terrestrial orchid that is endemic to New South Wales.

Prasophyllum unicum is a terrestrial, perennial, deciduous, herb with an underground tuber and a single leaf sheathing the flowering stem at the base.

The labellum is spatula-shaped with a thread-like tip, and a two thick, parallel, dark reddish calli.

[2] Prasophyllum unicum was first formally described in 1942 by Herman Montague Rupp in The Victorian Naturalist from specimens collected in Normanhurst in the same year.

[4] The specific epithet (unica) means "unique", "because it stands alone among all forms hitherto described".