Lanham is situated in the central portion of Prince George's County, Maryland, roughly 10 miles northeast of downtown Washington, D.C. It lies within the Atlantic Coastal Plain, a geographic region characterized by relatively flat land, winding creeks, and dense deciduous forests typical of the mid-Atlantic.
The community is defined largely by its man-made borders, including major arterial highways such as Interstate 495 (the Capital Beltway) to the west and US Route 50 (John Hanson Highway) to the south. Lanham is intersected by several small streams, including Folly Branch, which feed into the larger Anacostia River watershed. The area features a mix of mature suburban tree canopies, parks, and residential landscaping.