Moraine is a city in Montgomery County, Ohio, United States. Situated on the banks of the Great Miami River, Moraine is an inner suburb of Da…Moraine is a city in Montgomery County, Ohio, United States. Situated on the banks of the Great Miami River, Moraine is an inner suburb of Dayton, Ohio and a part of the Dayton metropolitan area. The population was 6,393 at the 2020 census.