Pionia (Ancient Greek: Πιονία) or Pioniai (Πιονίαι) was a town in the interior of ancient Mysia, on the river , to the northwest of Antandrus, and to the northeast of Gargara. Under the Roman dominion it belonged to the jurisdiction of Adramyttium, and in the ecclesiastical notices it appears as a bishopric of the Hellespontine province. The bishop Aetius represented the city at the Council of Ephesus. No longer the seat of a residential bishop, it remains a titular see of the Roman Catholic Church. Its site is located near Gömeniç in Asiatic Turkey.