Sloane Square is a London Underground station in Sloane Square, Belgravia. It is between South Kensington and Victoria on the District Line and Circle Line, and is in Travelcard Zone 1.

It opened as part of the original route of the Metropolitan District Railway (now the District line) on 24 December 1868. The current station is largely a post-World War II rebuild, the original Victorian station having been destroyed by enemy boming in 1940.

The station crosses the valley of the River Westbourne, which runs through Hyde Park as the Serpentine Lake, and originally crossed the Knight's Bridge at Knightsbridge. The river itself runs across the centre of the station, crossing above the platforms in an iron pipe.

The river had a significant effect on the station. The station could not be built above the river because that would be at least partly above ground level, and would be very costly, blocking major roads and buildings. Neither could the station be at the same level as the river, as the river would either block the trains and the platforms, or the water would have to be raised and lowered at either sides by means of an expensive pumping system. In consequence the station is unusually deep for a sub-surface line (as opposed to deep level lines), pushing the limits of the technology when it was built.

Access to the surface is currently by escalators from each of the side platforms, which replaced steps in view of the depth of the station below the river. The surrounding area has a high level of shops aimed at the more expensive end of the market, and in consequence the station has relatively low patronage, since attendance at the shops is usually by means of taxi.