Cladonia wainioi or the Wainio's cup lichen[1] is a species of cup lichen found in boreal and arctic regions of the Russian Far East and northern North America.

The specific epithet honours Finnish lichenologist Edvard August Wainio.

[4] They suggested that C. wainioi is "rather distinct in its cladinioid branching and its production of merochlorophaeic acid".

Cladonia wainioi has greenish to brownish mineral-grey podetia that are covered with small scales (squamulate).

[5] Cladonia wainioi grows in boreal bogs and rocks in arctic regions of eastern Asia and northern North America.