The 2020 census found 1,509 people in the township.

Located in the northeastern part of the county, it borders the following townships: No municipalities are located in Fairfield Township, although the unincorporated community of Somerdale lies in the northeastern part of the township.

[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, 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.

The current trustees are William Beans, Kenneth Brown, and John Dunn, and the fiscal officer is Jennifer Brown.