Waldorf is a census-designated place in Charles County, Maryland, United States. Located 23 miles (37 km) south-southeast of Washington, D.C., Waldorf is part of Southern Maryland. Its population was 81,410 at the 2020 census. Waldorf has experienced dramatic growth, increasing its population 16-fold from fewer than 5,000 residents in 1980 to its current population. It is now the largest commercial and residential area in Southern Maryland as well as a major suburb in the Washington metropolitan area.

Charles County is a county located in the U.S. state of Maryland. As of the 2020 census, the population was 166,617. The county seat is La Plata. The county was named for Charles Calvert (1637–1715), third Baron Baltimore. Charles County is part of the Washington metropolitan area and the Southern Maryland region.