Ottawa Township is one of the fifteen townships of Putnam County, Ohio, United States.

The 2020 census found 8,034 people in the township.

Located in the central part of the county, it borders the following townships: Two villages are located in central Ottawa Township: Ottawa, the largest village in and county seat of Putnam County; and Glandorf, which lies northwest of Ottawa.

[6] 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,[7] 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.