The 2020 United States census reported 3,077 people living in the township,[3] down from 3,506 in 2010.

[4] Located in the western part of the county, it borders the following townships: Part of the village of St. Paris is located in southern Johnson Township, and the unincorporated community of Millerstown lies in the township's east.

The Kiser Lake State Park and wetlands preserve are also located here.

It was named for Major Silas Johnson (Johnston), a Revolutionary War veteran and the first white person to settle in the area in 1802.

[5] 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.