East Massapequa is a hamlet and census-designated place (CDP) located within the Town of Oyster Bay in Nassau County, New York, United States. The population was 19,069 at the 2010 census. The hamlet lies in New York's 3rd congressional district. The most eastern third portion of East Massapequa (within the Amityville School District) was previously the hamlet of West Amityville and started utilizing a Massapequa mailing address in 1975.