The Clink Restaurant, based in HMP Brixton, has won Best Ethical Restaurant in the 2015 Observer Food Monthly Awards, in association with Cuisinart.
The winners were announced at a ceremony in London last night.
The show was co-hosted by Claudia Winkleman, Observer Food Monthly editor Allan Jenkins, and Brixton local and food critic Jay Rayner.
The Clink Restaurant, which gives practical skills to prisoners allowing them to learn and engage with the wider public, was awarded best ethical restaurant.
The high-end diner is staffed by inmates and several paid staff and trainers.
It is the third restaurant of its kind to be opened by charity The Clink, which hopes the new skills inmates pick up will help them to find a job after leaving prison.
The charity also operates restaurants in Cardiff and High Down in Surrey.
Opening in February last year, the Brixton restaurant has quickly garnered acclaim from critics, and can now add the Observer’s award to its name.
Now in their twelfth year, the awards – which are voted for by both Observer readers and a judging panel – champion the best producers, restaurants, retailers and bloggers in the UK.
Other winners at the awards ceremony included Max’s Sandwich shop, in Crouch Hill, The Camberwell Arms, and Dandelyan on the South Bank.