Cortinarius boulderensis, commonly known as the cinnamon-ringed webcap, is a species of mushroom in the family Cortinariaceae.
The cap of Cortinarius boulderensis starts out conical, before sometimes becoming campanulate or almost flat. It is about 1.5-4 centimeters in diameter and brown in color. The gills start out grayish, before becoming brown in age. The stipe is about 3-8 centimeters long and 3-7 millimeters wide. It is hollow at the base. A cortina is present. The spore print is rusty brown. There is an orange band on the stipe.
Cortinarius boulderensis is found in coniferous forests. It is more commonly found in old-growth forests, and fruits during autumn.