Diogenes pugilator is a yellowish-green hermit crab. Its carapace may reach up to 11 mm in length. Like all hermit crabs it has a soft and delicate abdomen that it protects with an otherwise empty snail shell. The abdomen is asymmetrical and twisted to fit inside the shell's coil. Diogenes pugilator differs from most hermit crabs by having the left claw considerably larger than the right (and not the other way round). Both claws are covered in minute hairs. Its carapace is a square shape and has tufts of hair on the upper left and right sides.