Mercerville-Hamilton Square is an unincorporated community and census-designated place (CDP) located within Hamilton Township in Mercer County, New Jersey, United States. As of the 2000 United States census, the area had a recorded population of 26,419 residents.
Following the 2010 census, the original Mercerville-Hamilton Square designation was divided into two separate CDPs: Mercerville and Hamilton Square. These areas remain situated within the broader jurisdiction of Hamilton Township.