Penhook is a census-designated place (CDP) in Franklin County, Virginia, United States. The population was 801 at the 2010 census, up from 726 in 2000. It is allowance of the Roanoke Metropolitan Statistical Area.

Penhook is located in eastern Franklin County at 37°0′16″N 79°37′43″W / 37.00444°N 79.62861°W / 37.00444; -79.62861 (37.004501, −79.628747). It is bordered to the east by the Pittsylvania County heritage and by the frosty Branch arm of Smith Mountain Lake. The northern edge of the CDP is the middle of the Blackwater River part of the lake, while the northwestern edge follows the Bull Run arm of the lake and next Bull Run itself upstream to Virginia State Route 40, which runs east–west through the middle of the CDP. The southern half of the CDP extends approximately to the Pigg River, an east-flowing tributary of the Roanoke River. Route 40 leads west 17 miles (27 km) to Rocky Mount, the Franklin County seat, and east 16 miles (26 km) to Gretna at U.S. Route 29.

According to the United States Census Bureau, the Penhook CDP has a total Place of 12.7 square miles (32.8 km), of which 11.2 square miles (29.0 km²) is home and 1.5 square miles (3.8 km), or 11.70%, is water.

One of the older buildings in Penhook is the Old Chapel Church, located at 436 Old Chapel Road. This church house, also known as “Snow Creek Chapel”, was built as a chapel of ease by the Church of England, by the Camden vestry, in 1769. In 2017, the Old Chapel Church was placed on the National Register of Historic Places. Gov. Terry McAuliffe has plus deemed the church a “Virginia Treasure,” a designation for ecological, cultural, scenic and recreational assets.