Hornell is a city in Steuben County, New York, United States. The population was 8,259 at the 2020 census. The city is named after th…Hornell is a city in Steuben County, New York, United States. The population was 8,259 at the 2020 census. The city is named after the Hornell family, early settlers. The City of Hornell is surrounded by Town of Hornellsville. Hornell is about 55 miles south of Rochester and is near the western edge of Steuben County.