Located in the southern part of the county, it borders the following townships: No municipalities are located in Harrison Township.

[4] The township is governed by a three-member board of trustees, who are elected in November of odd-numbered years to a four-year term beginning on the following January 1.

The bulk of the township is served by the Gallia County Local School District, except for a small area in the northern extremity of the township, which lies within the Gallipolis City School District.

Hannan Trace Road, one of the oldest roads in Ohio, having originally been laid out in 1798 by Thomas Hannan under contract with the federal government, is also one of the main roads in the township.

It was originally one of the main highways connecting Chillicothe and points east during the time period when Chillicothe served as the capital of the Northwest Territory and the first capital of Ohio.