As of the 2020 census, the population was 429, including 70 people in the village of Graysville.

Located in the southwestern part of the county, it borders the following townships: The village of Graysville is located in northern Washington Township, and the unincorporated community of Rinard Mills lies along the Little Muskingum River in the township's southwest.

It is one of forty-three Washington Townships statewide.

[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.

There is also an elected township fiscal officer,[5] who serves a four-year term beginning on April 1 of the year after the election, which is held in November of the year before the presidential election.