Lamoille County is a county located in the U.S. state of Vermont. As of the 2020 census, the population was 25,945, and it is the third-least populous county in Vermont. Its shire town (county seat) is the town of Hyde Park, while Morristown is the county's largest town by population as well as its main commercial center. The county was created in 1835 from portions of Orleans, Franklin, Washington, and Chittenden Counties and was organized the following year.