Chantilly is an unincorporated community in western Fairfax County in Northern Virginia and a census-designated place (CDP). A portion of Chantilly is located within the South Riding, Virginia CDP located to the immediate west, but within Loudoun County, Virginia. The Chantilly CDP population was 23,039 as of the 2010 census. Chantilly is named after an early-19th-century mansion and farm, which in turn took the name of an 18th-century plantation that was located in Westmoreland County, Virginia.