A mammal tooth discovered from the upper Eocene Ergilin Dzo Formation of southeastern Mongolia is identified as an upper second molar of a small amphicyonid (Mammalia: Carnivora). It is similar to Cynodictis, which is a primitive amphicyonid from the late Eocene to early Oligocene of Europe, in overall size, relative size of the trigon cusps, and smooth lingual cingulum. However, it differs from Cynodictis and other amphicyonids in having an extremely thick lingual cingulum that bulges posterolingually and a parastyle that positions anterior to the paracone, indicating that it belongs to a new genus of the family. Reappraisals of previously reported “Cynodictis” materials from the Paleogene of Asia imply that none of them belong to the Amphicyonidae, and only the present material confirms the existence of an amphicyonid in the Eocene of northern East Asia. This opens questions on the previously proposed existence of Cynodictis and migration of amphicyonids in the Paleogene of Asia.