Charlestown Township is one of the eighteen townships of Portage County, Ohio, United States. The 2000 census found 2,003 people in the township. Charlestown Township covers an area of 23.1 sq mi (60 km2). Charlestown Township was organized in 1814. A post office called Charlestown was established in 1820, and remained in operation until 1904.
Some of the township is within Camp Ravenna Joint Military Training Center, which was created in 1941 in response to WW2.
West Branch State Park and the Michael J Kirwan reservoir are located in the southern portion of the township.