Nanjemoy Creek is a tidal tributary of the Potomac River in Charles County, Maryland, United States, located between Cedar Point Neck and Tayloe's Neck. Its watershed area (excluding water) is , with 2% impervious surface in 1994.
The Nature Conservancy established its Nanjemoy Creek Preserve in 1978, which protects more than in the watershed. There is a large great blue heron rookery located at Nanjemoy Creek.
Blossom Point, a part of Harry Diamond Laboratories, and operated by the U.S. Army, is located on Cedar Point Neck, and unexploded ordnance (UXO) may be present within firing fans, which extend into both Nanjemoy Creek and the Potomac River.
The rural community of Nanjemoy is in the area around Nanjemoy Creek.
The following variant names have been listed on the Geographic Names Information System by the United States Geological Survey.