Black Rock is a city in Lawrence County, Arkansas, United States, along the Black River. The population was 662 at the 2010 census.
Black Rock is located in northern Lawrence County at 36°6′28″N 91°5′56″W (36.107794, -91.098913), at the eastern edge of the Ozarks. It sits on the west side of the Black River, a south-flowing tributary of the White River.
U.S. Routes 63 and 412 run concurrently through the south side of the city, leading northwest 30 miles (48 km) to Hardy. To the southeast, US 412 leads 9 miles (14 km) to Walnut Ridge, the Lawrence county seat, while US 63 leads 8.5 miles (13.7 km) to Hoxie.
According to the United States Census Bureau, the city of Black Rock has a total area of 3.4 square miles (8.9 km2), of which 3.3 square miles (8.5 km2) are land and 0.2 square miles (0.4 km2), or 4.08%, are water.
As of the census of 2000, there were 717 people, 284 households, and 199 families residing in the city. The population density was 218.6 people per square mile (84.4/km2). There were 334 housing units at an average density of 101.8 per square mile (39.3/km2). The racial makeup of the city was 99.02% White, 0.14% Native American, and 0.84% from two or more races. 0.28% of the population were Hispanic or Latino of any race.