Kings Park is a hamlet and census-designated place in the Town of Smithtown, Suffolk County, New York, United States, on Long Island. The population was 17,282 as of the 2010 census. It is an unincorporated hamlet of Smithtown, New YorkIt is bordered by Nissequogue to its east across the Nissequogue River, by Fort Salonga to its west, by Commack to its southwest, and by the hamlet of Smithtown to its southeast. Kings Park is noted for its schools, numerous parks, and natural environment. Its relative tranquility prompted it to be the site of the Kings Park Psychiatric Center instead of New York City.