Polyporus admirabilis is often distinguished by odor. It has a very strong and unpleasant smell that can often be described as sickeningly sweet. Specimens are often found in clusters of four or more laterally attached caps. Occasionally a single, rosette-shaped pileus can be found; esp. in a young specimen. Cap size varies from 10 to 36cm in mature fruiting bodies. Pileus can be concave or depressed when viewed from above and older samples may have the appearance of a rudimentary stalk.
The flesh of the fruiting body is generally a light cream color and is thick, tough and fibrous. Mature specimens can reach a thickness of up to five cm. The spore bearing surface is usually a clean white with 3-5 pores per mm2. Many specimen have round, congruous pores but on occasion the pores may become angular, especially with age.