Franklin is a city in Warren County, Ohio, United States, along the Great Miami River. The population was 11,690 at the 2020 census. The city lies about 15 miles (24 km) southwest of Dayton and 33.5 miles (53.9 km) northeast of Cincinnati. Ohio State Routes 73, 123 and 741 pass through Franklin, while Interstate 75 is routed to the east side of the city.

Warren County is a county located in the southwestern part of the U.S. state of Ohio. As of the 2020 census, the population was 242,337. Its county seat is Lebanon and largest city is Mason. The county is one of Ohio's most affluent, with the highest median income of the state's 88 counties. The county was established on May 1, 1803, from Hamilton County; it is named for Dr. Joseph Warren, a hero of the Revolution who sent Paul Revere and the overlooked William Dawes on their famous rides and who died at the Battle of Bunker Hill. Warren County is part of the Cincinnati, OH-KY-IN Metropolitan Statistical Area.