The B223 is an urban B-road in south London, running parallel to the Chatham Main Line.
It starts on the A23 between the two railway bridges by Brixton station. It heads southeast along Atlantic Road, going under a railway line and crossing the A2217 at a set of traffic lights.
The B223 continues south along Railton Road as far as Herne Hill station, the next on the line. From here the original line of the B223 followed the full length of the road to end at the A2214/A215 junction in the shadow of the railway bridge. Northbound traffic was later removed onto Hurst Street, some distance to the west, and around 2010 the original eastern end of the B223 was closed to traffic to provide a pedestrian area and simplify the junction, so southbound B223 traffic follows Rymer Street, parallel to Hurst Street. The southern end of the B223 is therefore on the A2214 opposite Brockwell Park.