Phlegmacium prasinocyaneum is a species of mushroom producing fungus in the family Cortinariaceae.
It was described in 1939 by the mycologist Robert Henry who classified it as Cortinarius prasinocyaneus.
In 2022 the species was transferred from Cortinarius and reclassified as Phlegmacium prasinocyaneum based on genomic data.
It is found in Western Europe and Scandinavia. It is endangered.