The invasive sabellid polychaete Branchiomma bairdi McIntosh, 1885 was collected in the Boughrara Lagoon (southern Tunisian coast) between 2012 and 2013. This species was originally described from Bermuda and has been widely reported in the Caribbean Sea. It has been considered as non-indigenous species on the Pacific coast of Panama and the California Gulf. Recently, B. bairdi was recorded along the Italian and Turkish coasts, Australia, Canary and Madeira Islands. It was suggested that the commercial shipping is the most likely vector for the introduction of the species to Mediterranean Sea. A description of the species along with a discussion of its systematic position and ecology are provided.