Northridge is an unincorporated community in Harrison Township in Montgomery County, Ohio, United States. It was delineated as a census-designated place (CDP) for the 2000 census, at which time its population was 8,487. It is located directly north of the city of Dayton and is part of the Dayton Metropolitan Statistical Area.

Harrison Township is one of the nine townships of Montgomery County, Ohio, United States. As of the 2020 census, the population was 21,814.