Wyandanch is a hamlet and census-designated place (CDP) in Suffolk County, New York, United States. It is located in the Town of Babylon. As of the 2010 census, the CDP population was 11,647.

Wyandanch is an unincorporated hamlet in the Town of Babylon, in Suffolk County, New York. It is located approximately 11 miles east of the Village of Babylon and is bordered by the hamlets of Wheatley Heights and North Amityville to the north, Deer Park to the east, the hamlet of South Deer Park to the south, and Wheatley Heights to the west. The hamlet is part of the Town of Babylon and is served by the Wyandanch Union Free School District.

Wyandanch is home to a diverse population, primarily made up of African-American, Hispanic/Latino, and Caribbean-American residents. The hamlet has a history of poverty and crime, and has recently been the subject of revitalization efforts by the local government, nonprofits, and businesses. Wyandanch is home to an array of businesses and organizations, including a library, a community center, a youth center, a cultural center, and a number of churches.