A new genus and species of extinct inioid odontocete (Meherrinia isoni) is based on nine partial crania that probably originated from the late Miocene marine Eastover Formation in North Carolina, U.S.A. They were collected from the riverbed of the Meherrin River, a tributary of the Chowan River. Ossification of the mesethmoid and the tight inter-digitation of many sutures indicate that these specimens represent mature individuals. Key characteristics of the new inioid include maxillae that ‘squeeze’ the nasals into a slight hourglass shape and supraoccipital that is deeply wedged between the frontals and maxillae on the vertex. As compared to the extant iniid Inia geoffrensis (Amazon River dolphin) and the extant pontoporiid Pontoporia blainvillei (La Plata dolphin), Meherrinia is more plesiomorphic in having less elevated premaxillary eminences and supraorbital processes. In other respects Meherrinia is intermediate in morphology between the two extant genera of inioids. For example, the essentially symmetrical vertex is intermediate in height between the low and high vertices in Pontoporia blainvillei and Inia geoffrensis, respectively. A cladistic analysis of morphological and molecular data supports a sister-group relationship between Meherrinia and Inia; thus our new taxon is tentatively assigned to the Iniidae. If correct, this is the first iniid represented by diagnostic remains from marine deposits and just the second from North America.