Shelton is a city in Fairfield County, Connecticut, United States. The population was 40,869 at the 2020 United States Census. The city is part of the Naugatuck Valley Planning Region.

Fairfield County is a county in the southwestern corner of the U.S. state of Connecticut. It is the most populous county in the state and was also its fastest-growing from 2010 to 2020. As of the 2020 census, the county's population was 957,419, representing 26.6% of Connecticut's overall population. The closest to the center of the New York metropolitan area, the county contains four of the state's top 7 largest cities—Bridgeport (1st), Stamford (2nd), Norwalk (6th), and Danbury (7th)—whose combined population of 433,368 is nearly half the county's total population.