Both East Windsor Township and West Windsor Township were formed when Windsor Township was split on February 9, 1797, while the area was still part of Middlesex County. It was incorporated by an act of the New Jersey Legislature on February 21, 1798, as one of New Jersey's initial group of 104 townships. Portions of the township were taken to form Hightstown borough (March 5, 1853, within East Windsor; became independent c. 1894) and Washington Township (March 11, 1860, and known as Robbinsville Township since 2007). The township was named for Windsor Township, which was named for Windsor, England.