Glen Lyn is a town in Giles County, Virginia, United States, at the confluence of the East and New rivers. The population was 115 at the 2010 census, down from 151 at the 2000 census. It is part of the Blacksburg–Christiansburg Metropolitan Statistical Area.
Glen Lyn is located in northwestern Giles County at 37°22′23″N 80°51′39″W (37.373080, -80.860906), on both sides of the New River. It is bordered to the west by the East River and by the state of West Virginia. U.S. Route 460 passes through the town, leading east (upstream along the New River) 3 miles (5 km) to Rich Creek and west 15 miles (24 km) to Princeton, West Virginia. Pearisburg, the Giles County seat, is 12 miles (19 km) southeast (up the New River) via US 460, and Blacksburg is 34 miles (55 km) southeast.
According to the United States Census Bureau, Glen Lyn has a total area of 0.73 square miles (1.9 km2), of which 0.66 square miles (1.7 km2) are land and 0.1 square miles (0.2 km2), or 12.22%, are water.
The climate in this area has mild differences between highs and lows, and there is adequate rainfall year-round. According to the Köppen Climate Classification system, Glen Lyn has a marine west coast climate, abbreviated "Cfb" on climate maps.
As of the census of 2000, there were 151 people, 57 households, and 38 families living in the town.