Dearborn County is one of 92 counties of the U.S. state of Indiana. Located on the Ohio border near the southeast corner of the state, Dearborn County was formed in 1803 from a portion of Hamilton County, Ohio. In 2020, the population was 50,679. The county seat and largest city is Lawrenceburg. Dearborn County is part of the Cincinnati, OH-KY-IN Metropolitan Statistical Area.