Old Westbury is a village in the Towns of North Hempstead and Oyster Bay in Nassau County, on the North Shore of Long Island, in New York, United States. The population was 4,671 at the 2010 census.
The Incorporated Village of Old Westbury is one of the richest villages in the country as well as the second-richest zip code in the New York State, topped only by Harrison in Westchester County. In 2007, Business Week dubbed Old Westbury as New York's most expensive suburb. Old Westbury Gardens has been recognized as one of the three best public gardens in the world by Four Seasons Hotels magazine. The Long Island campus of the New York Institute of Technology is a life sciences and cybersecurity research institution located in Old Westbury.