State Route 171 or SR-171 is an American 73.355-mile (118.053 km) state highway that serves as a north-south connection between Northport and Hamilton through Fayette, Marion and Tuscaloosa Counties. SR-171 intersects US-43 at its southern terminus and SR-17 at its northern terminus.

State Route 171 begins at its intersection with US-43 in Northport. From this point, SR-171 travels in a northerly direction through rural portions of northern Tuscaloosa County in route to Fayette. In Fayette, SR-171 intersects SR-159 and US-43 near its central business district and both SR-129 and SR-102 on its north side. The route continues in its northerly track and intersects US-78 and Interstate 22 in route to its northern terminus at SR-17 in Hamilton. Additionally, between Fayette and its northern terminus SR-171 has a 37.869-mile (60.944 km) concurrency with US-43.