Part of London mayor Ken Livingstone's '100 Spaces for London' programme, the scheme will breathe new life into the traffic-clogged square, which is overlooked by William Crabtree's Grade II-listed Peter Jones store.
The practice has been asked to come up with two proposals, the first of which includes plans to increase the pedestrianised area by more than 50 per cent by reintroducing the original crossroads. A less radical option aims to keeps the current layout.
Public consultation on both proposals is set to get underway later this month.
Councillor Daniel Moylan, deputy leader of Kensington and Chelsea council, said: 'A vast amount of the space within Sloane Square is given over to unnecessary carriageway.
'The previous consultation clearly showed strong support for a radical change that would capture space for a pedestrian use without notable impairment to vehicular traffic.
'Working with award-winning architect Stanton Williams, we have now prepared a design that draws on traditional English streetscape elements and will make Sloane Square one of London's calmly impressive public spaces,' he added.
An exhibition outlining the options will be held at the gallery in Duke of York's Square, King's Road, until the 18 January.