Three new species of Carcinonemertes from the southeastern coast of Brazil are described: Carcinonemertes divae new species, Carcinonemertes caissarum new species and Carcinonemertes sebastianensis new species. They were found, respectively, associated with the crabs Libinia spinosa, Hepatus pudibundus and Menippe nodifrons, each a newly recorded host for Carcinonemertes. Characters not previously used to describe members of the family Carcinonemertidae, such as distance from ovaries to tip of head, distance from brain to tip of head and distance from stylet to tip of head are included in the descriptions of the new species and are discussed. The locations of these new carcinonemertid worms in their respective hosts are presented in detail and a novelty regarding the infestation site is registered.