The shop is located on the centre's upper terrace, adjacent to artist Jeppe Hein's Appearing Room Fountain – an artwork that shoots jets of water into the air.
The East London-based studio wanted to complement this water piece and so designed a kiosk for selling sun cream and accessories that could be used for jumping in the water fountain.
To continue the pool theme, the shop's base is covered in tiles and features a small pool ladder to emulate the aesthetics of public swimming baths.
"We were invited by the Southbank Centre to create an art installation and mobile retail structure that responded to the delightful transformation of the Southbank's site by Jeppe Hein's Appearing Rooms Fountain into one of play, water and public enjoyment," studio founder Nick Wood told Dezeen.
"Inspired by the tiled landscapes of public pools, and dreaming of drifting icebergs, we designed a durable mobile structure that unfolds and extends to become a retail stand selling sun cream and other poolside accessories to the public."
The designers also referenced David Hockney's painting A Bigger Splash, 1967, which depicts a pool beside a modern house disturbed by a large white splash of water.
They translated it to the structure's blue and white tiling, which looks like a pixelated graphic of the painting. The artwork's colour palette also influenced the shop's pink pool ladder and roof canopy.
The canopy opens and closes like a pair of wings, and a storage drawer slots into the main base. These features mean the shop can easily fold up and be moved around the location like a cart.
Mirrored and brushed gold surfaces on the underneath of the roof and inside the drawer were added to create watery reflections.
How About Studio, whose previous projects include one of last year's 13 RIBA Regent Street window installations, also created two other projects for this year's Festival of Love at the Southbank Centre – arches of light under Hungerford Bridge and an abstract image of two polar bears at Southbank Centre Square.
The Mobile Shop is one of a series of moveable structures that have appeared in London. Other projects include a town square that packs into a miniature clock tower on the back of a bike and a tiny performance venue based on 16th-century market stalls.
Photography is by GG Archard.