It usually has only one grass-like leaf at its base and up to eight bright, lemon-yellow flowers with a few dark markings.

The flowers are bright lemon-yellow with a few dark markings at the base of the dorsal sepal and labellum.

[1] Diuris unica was first formally described in 2006 by David Jones from a specimen he collected near Maryborough in 1986.

[2] The specific epithet (unica) is a Latin word meaning "only", "sole" or "singular",[3] referring to the single leaf of this orchid.

[1] This orchid grows in wallum and sandy heath in coastal and near-coastal districts in south-eastern Queensland and disjunctly in northern New South Wales.