Washington Township is one of the fifteen townships of Harrison County, Ohio, United States. As of the 2020 census the population was 640.

Harrison County is a county located in the U.S. state of Ohio. As of the 2020 census, the population was 14,483, making it the fifth-least populous county in Ohio. Its county seat and largest village is Cadiz. The county is named for General William Henry Harrison, who was later President of the United States.