It has a single thin leaf and up to twenty five dark purplish-black and green flowers.

Genoplesium tasmanicum is a terrestrial, perennial, deciduous, herb with an underground tuber and a single thin leaf 80–180 mm (3–7 in) long with the free part 15–22 mm (0.6–0.9 in) long.

There is a dark purplish-black callus in the centre of the labellum and extending nearly to its tip.

[1][5] The specific epithet (tasmanicum) is the Latinised version of "Tasmania".

[3] Genoplesium tasmanicum is widespread and common in Tasmania where it mostly grows with herbs, shrubs or grasses at altitudes up to 250 m (800 ft).