Located in the southwestern corner of the county, it borders the following townships: Two incorporated villages are located in Harrison Township: Hollansburg in the northwest, and part of New Madison in the east.

[4] The area within the modern borders of Harrison Township was first settled in 1810, but it was abandoned after Native American attacks; no settlers returned until after the end of the War of 1812.

[5]: 557  American soldiers built two forts in 1813 for that war within the bounds of the present township: Fort Black, near Main Street in present-day New Madison,[5]: 556  and Fort Nesbitt, in Section 32.

[5]: 557  After the war's end, some settlers returned to the area, along with many former residents of Kentucky.

[5]: 558 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.