Miamisburg is a city in southern Montgomery County, Ohio. The population was 19,923 at the 2020 census.

​The city is home to a number of historic sites, including the Miamisburg Mound, which is the largest conical burial mound in Ohio. Miamisburg is also home to a number of festivals and events throughout the year, including the Miamisburg Car Show, the Miamisburg Fourth of July Celebration, and the Miamisburg Pumpkin Festival.