Chittenden County () is the most populous county in the U.S. state of Vermont. As of the 2020 census, its population was 168,323. The county seat is Vermont's most populous municipality, the city of Burlington. The county has over a quarter of Vermont's population and more than twice the population of Vermont's second-most populous county, Rutland. The county also has more than twice the population density of Vermont's second-most dense county, Washington. The county is named for Vermont's first governor and one of the framers of its constitution as an independent republic and later U.S. state, Thomas Chittenden.
It is one of the three counties that comprise the Burlington metropolitan area, along with the counties of Franklin and Grand Isle to the north and northwest, respectively. The University of Vermont, Vermont's largest university, is located in the county, as well as its affiliated hospital, the UVM Medical Center (which is Vermont's largest hospital and collectively forms the largest employer in the state along with the university). Vermont's largest private employer (GlobalFoundries) and largest airport (Patrick Leahy Burlington International Airport) are in the localities of Essex Junction and South Burlington, respectively.
The Vermont Army National Guard is based at Camp Johnson in the town of Colchester. The Vermont Air National Guard is based at the Burlington Air National Guard Base on the grounds of the international airport in South Burlington.
Geography
According to the United States Census Bureau, the county has a total area of , of which (13%) are covered by water. It is the third-smallest county in Vermont by area.
Originally, Chittenden County contained parts of other counties. It included all of today's Franklin, Grand Isle, and Lamoille counties, and parts of today's Orleans, Washington, and Addison counties.
thumb|right|Western face of Mount Mansfield from Underhill, Vermont
The town of Underhill in Chittenden County is home to the highest summit within the state, Mount Mansfield, which has a peak elevation of above sea level.
Adjacent counties
- Addison County – south
- Clinton County, New York – northwest
- Essex County, New York – west
- Franklin County – north
- Grand Isle County – northwest
- Lamoille County – northeast
- Washington County – southeast