Callistosporium luteo-olivaceum is a species of agaric fungus in the family Callistosporiaceae. It was originally described in 1859 as Agaricus luteo-olivaceus by Miles Joseph Berkeley and Moses Ashley Curtis in 1859. Rolf Singer transferred it to Callistosporium in 1946. The fungus has an extensive synonymy.
The brownish mushroom has caps up to wide. The gills are yellowish and close. The stem is long, fibrillose and hollow, with yellowish tomentum near the base. The spores are colorless, producing a whitish print or a yellow color in ammonia. The species can resemble Tricholomopsis aurea, T. sulfureoides, and Gymnopilus picreus.
Although rare, C. luteo-olivaceum is widely distributed in temperate and tropical areas of Europe and North America. In 2014, it was reported growing in pine forests in Western Himalaya, Pakistan. The species is inedible.