Great Falls is a census-designated place in Fairfax County, Virginia, United States. The population at the 2020 census was 15,953. It is named for the nearby Great Falls of the Potomac River.

Colonial farm settlements began to form in the area as early as the late 1700s.

Early on, the village was known as Forestville (unofficially, since there was already a Forestville with a Post Office), but was renamed Great Falls in 1955.

Great Falls is located on Virginia State Route 7 in Northern Virginia, Great Falls is 15 miles (24 km) west-northwest of downtown Washington, D.C., and 10.5 miles (16.9 km) north of Fairfax, the county seat.

Great Falls lies in the Piedmont upland on the right bank of the Potomac River. The Potomac River forms the northern and eastern borders of the CDP, and several of its tributaries flow north and east through the CDP. From north to south, these include Nichols Run, Clarks Branch, and Difficult Run. Difficult Run (along with Leesburg Pike) forms the southern border of the CDP. Two of its tributaries, Captain Hickory Run and Piney Run, flow southeast through the southern part of the CDP. The Great Falls of the Potomac River, the community's namesake, are on the east side of the CDP.

According to the United States Census Bureau, the CDP has a total area of 25.66 square miles (66.5 km²) of which 25.42 square miles (65.8 km²) is land and 0.24 square miles (0.62 km²) is water.

As a suburb of Washington, D.C., Great Falls is a part of both the Washington Metropolitan Area and the larger Baltimore-Washington Metropolitan Area. It is bordered on all sides by other Washington suburbs, including: Darnestown and Travilah, Maryland to the north, Potomac, Maryland to the east, McLean to the southeast, Wolf Trap to the south, Reston and Dranesville to the southwest, Sterling to the west, and Lowes Island to the northwest.

This section includes some information from the 2022 American Community Survey