Windsor was a township (1751–1797) in early Middlesex County, in an area that is now within Mercer County, New Jersey, United States.
The Windsor area was within Piscataway Township when it was chartered on December 18, 1666.
This changed upon the formation of Middlesex County in 1683.
[2] Its borders encompassed today's West Windsor Township, all of present-day Princeton up to Nassau Street, and pre-partition East Windsor Township.
[3]: 165 The boundaries of old Windsor Township now lie within Mercer County, because the February 22, 1838 formation Mercer County took West Windsor Township and portions of East Windsor Township from Middlesex County.