Located in the northwestern part of the county, it borders the following townships: No municipalities are located in Decatur Township.

Statewide, the only other Decatur Township is located in Washington County.

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.

All of Decatur Township's educational services are provided by the Rock Hill Local School District, which provides Pre-K through 12th grades.