New Middletown is a village in Mahoning County, Ohio, United States. The population was 1,682 at the 2000 census. New Middletown is served by a branch of the Public Library of Youngstown and Mahoning County. New Middletown apartments for rent comparison page shows most up to date rent information on New Middletown apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.