Chubby Cloud was installed in the main room of Banqueting House, a neo-classical 17th century building designed by Inigo Jones, for three days.
Visitors were asked to dress in protective white boilersuits before climbing onto the gigantic, soft structure.
Once aboard, they could either jump around, or lie back and admire the artwork overhead – the only surviving ceiling painting by Flemish artist Peter Paul Rubens.
The beanbag was big enough to hold up to 90 people at a time. Hindmarch described it as the largest beanbag in the world.
She explained that it was designed to match her Chubby Collection of bags and accessories.
"Chubby Cloud is an experimental installation," she said ahead of the launch. "Inspired by our Chubby Collection, the world's biggest beanbag will immerse people in our brand whilst listening to and experiencing things that we love."
Hindmarch developed the installation with beanbag manufacturer Precision Stitching. They produced a series of small-scale prototypes to test how the beanbag behaved, before building the final product.
During London Fashion Week, which took place from 14 to 18 September, it hosted a series of live talks, meditation and music performances. These included bedtime stories read by fashion model Poppy Delevingne and a conversation between to Serpentine Galleries CEO Yana Peel and designer Marc Quinn.
The project forms an extension of Hindmarch's Chubby Hearts over London campaign, which saw the designer install heart-shaped balloons across the city for Valentine's Day.
Accompanying the installation was a pop-up café and shop that sold bespoke products, ranging from cushions and eye masks to marshmallows.
Other designs unveiled during the latest London Fashion Week included a showcase of garments by three emerging designers.