New records of the Indo-Pacific seastar Mithrodia clavigera (Lamarck, 1816) include the north-central Gulf of Mexico, southeastern Florida, and Ascension Island. Material includes in-situ photographs, specimens from our own field collections, and museum specimens. This species was previously reported in the Atlantic basin in the 1880s off Brazil and in the western Caribbean Sea in the late 1960s and early 1970s. More recent findings are attributable to the advent of SCUBA, seafloor photography, and genetic analysis. The presence of M. clavigera in the Atlantic Ocean and adjacent waters probably represents a former connection with populations in the eastern Pacific Ocean before the rise of the Isthmus of Panama. Our observations here of specimens collected off Palm Beach and Fort Lauderdale, Florida, and the Gulf of Mexico add to our understanding of this species' behavior and ecology.