Fairfield is a city located in southern Butler County, Ohio, in the United States. Situated on the east bank of the Great Miami River, it functions as a suburb approximately 25 miles (40 km) north of Cincinnati.
The city was incorporated in 1955 from portions of Fairfield Township and encompasses the former hamlets of Symmes Corner, Fair Play, Furmandale, and Stockton. As of the 2020 census, the population of the city was 44,907.
The community is served by the Fairfield City School District, which ranks as one of the largest school districts in Ohio. The district provides educational services to both the residents of the city and those within Fairfield Township.