Ottawa is a city in, and the county seat of, Franklin County, Kansas, United States. It is located on both banks of the Marais des Cygnes River near the center of Franklin County. As of the 2020 census, the population of the city was 12,625. It is the home of Ottawa University.

Franklin County is a county located in the eastern portion of the U.S. state of Kansas. Its county seat and most populous city is Ottawa. As of the 2020 census, the county population was 25,996. The county was named for Benjamin Franklin, a founding father of the United States. Formerly it was considered part of the Kansas City metropolitan area, but was removed in 2013.