Millville is a town in Sussex County, Delaware, United States. The population in 2020 was 1,825, It is part of the Salisbury, Maryland-Delaware Metropolitan Statistical Area and lies within Baltimore Hundred.

Sussex County is located in the southern part of the U.S. state of Delaware, on the Delmarva Peninsula. As of the 2020 census, the population was 237,378, making it the state's second most populated county only behind New Castle and ahead of Kent. The county seat is Georgetown.