Winooski is a city in Chittenden County, Vermont, United States. Located on the Winooski River, as of the 2020 U.S. census the municipal population was 7,997. The city is the most densely populated municipality in northern New England, an area comprising the states of Maine, New Hampshire, and Vermont. It is the smallest of Vermont's 10 cities by area, though the city of Vergennes has the smallest population.