The A24 is a major road in England that runs for 53.2 miles (85.6 km) from Clapham in south-west London to Worthing on the English Channel in West Sussex via the suburbs of south-west London, as well as through the counties of Surrey and West Sussex.

Between Clapham and Dorking, the A24 closely follows the route of the old Roman road Stane Street. The Morden branch of the Northern line runs under the road from Clapham via Colliers Wood to Morden. Cycle Superhighway 7 also runs along the road from Clapham to Colliers Wood.

The A24 starts at a junction with the A3 at the northeastern corner of Clapham Common, near Clapham Common tube station in the London Borough of Lambeth. South of Clapham Common station, the London Underground Northern line runs beneath the A24, following its route southbound. The A24 runs along the eastern perimeter of the Common, before meeting the South Circular near Clapham South tube station. Along this stretch of road, Cycle Superhighway 7 (CS7), which begins in the City of London, leaves the A3/Clapham High Street and follows the route of the A24. CS7 is marked by blue paint on either side of the road.

Passing Clapham South, the A24 and CS7 enter the London Borough of Wandsworth. The routes are carried by Balham Hill, before becoming Balham High Road as they pass Balham station. Leaving Balham to the south, the A24 and CS7 arrive at Tooting Bec station at a junction with the A214.

Beyond Tooting Bec, the road is named Upper Tooting Road, before it becomes Tooting High Street as it passes Tooting Broadway station. At the station, the A24 and CS7 meet the A217/Garratt Lane. St George's Hospital is situated to the northwest of the A24, west of Tooting Broadway station. The routes leave the London Borough of Wandsworth, and Inner London, a short distance to the south of Tooting.

The A24 and CS7 enter the London Borough of Merton as they cross via a railway bridge over the Sutton Loop Line, between Haydons Road and Tooting stations. The routes are carried by High Street Colliers Wood. The routes meet Colliers Wood tube station, where CS7 finishes. The A24 then meets the A238/Merton High Street, at which point the route turns left to become Christchurch Road. The Northern line also no longer follows the route of the A24 at this point, instead following that of the A238 towards South Wimbledon.

At a crossroads in Merton, Christchurch Road continues southwards as the A236 (towards Mitcham). The A24 turns right onto Merantun Way, crossing the River Wandle as it leaves Colliers Wood and Merton.

The road turns left onto Morden Road at a junction with the A219. It passes Morden Industrial Area, Morden Hall Park and the A297 before reaching Morden Underground station. As London Road it passes under the railway bridge by Morden South railway station. It passes the junction with the A239 Central Road next to Morden Park before becoming Epsom Road. The road runs through Lower Morden for a short distance and passes by Morden Cricket Club before exiting the borough.