It is about 3.5 centimetres (1.4 in) long, can be found in pools on the upper shore and at the mean tide level down to a depth of approximately 140 metres (460 ft), with smaller specimens generally found in rock pools around the middle shore and lower shore regions, with larger individuals at depth. P. bernhardus is an omnivorous detritivore that opportunistically scavenges for carrion and which can also filter feed when necessary.
Pagurus bernhardus uses shells of a number of gastropod species for protection, including Littorina littorea, Littorina obtusata, Nucella lapillus and Buccinum. In the warmer parts of its range, the sea anemone Calliactis parasitica is often found growing on the shell occupied by Pagurus bernhardus. In colder waters, this rôle is filled by Hormathia digitata.