Miamisburg is a city in Montgomery County, Ohio, United States. The population was 20,181 at the 2010 census. It is part of the Dayton Metropolitan Statistical Area. Miamisburg is known for its large industry and retail factors commercial business area, which is partially located in Miami Township, but is probably most famous for being the home to the Miamisburg Mound. Miamisburg borders Miami Township, Springboro, and West Carrollton. The sister city of Miamisburg is Owen Sound, Ontario.