Ōe is located in mountainous central Yamagata. Like many small towns in Japan, Ōe is a collection of smaller hamlets. Elevation rises and populations decrease from east to west. The easternmost hamlet is Aterazawa, and contains about 4/5 of the town's population. The town extends from the west end of the central part of the Yamagata basin to the Asahi Mountains. In addition, it has several enclaves in Sagae city and Nakayama town, bordering the east. Administratively, the town area is divided from the east into the Sazawa, Hongo, and Shichiken districts. The Mogami River forms the eastern border of the town.
