We describe cranial, mandibular, and dental remains of five individuals of the giant mustelid Eomellivora piveteaui Ozansoy, 1965, from the late Miocene (MN10) site of Cerro de los Batallones (Madrid, Spain)—the first complete cranial remains recorded for this species and the most complete remains of the genus. This new sample enables a review of the systematic status of Eomellivora, leading us to accept as valid the species E. piveteaui Ozansoy, 1965, E. wimani Zdansky, 1924, E. ursogulo (Orlov, 1948), and E. hungarica Kretzoi, 1942. Our phylogenetic hypothesis indicates that Eomellivora is the sister taxon of the extant Mellivora capensis and E. piveteaui had a common ancestor within the crown group E. wimani—E. ursogulo. Eomellivora piveteaui was specialized for a more hypercarnivorous diet than the largest extant terrestrial mustelids, although it also had some derived bone-crushing adaptations. Eomellivora piveteaui had an active predatory role in the late Miocene carnivore faunas, exploiting both small and relatively large prey.