Cortinarius rotundisporus was initially described by naturalists John Burton Cleland and Edwin Cheel in 1918.

It is a member of the subgenus Myxacium within the genus Cortinarius; these species are characterized by the presence of a viscid to glutinous outer veil and stipe.

Its specific name is derived from the Latin rotundus "round", and Ancient Greek spora "seed".

The slender 5–7.5 cm (2–3 in) stipe lacks a ring; it is pale yellow or white with a tinge of the cap colour.

[5] Fruit bodies are found in eucalypt forests and rainforests,[2] and occasionally cleared areas.