According to the United States Census Bureau, the township has a total area of 37.9 square miles (98.1 km²), of which, 37.8 square miles (98.0 km²) of it is land and 0.04 square miles (0.1 km²) of it (0.05%) is water.
Oswayo Township is bordered by New York to the north, Genesee Township to the south, Allegany Township and the borough of Oswayo to the south and Sharon Township to the west.