The company's Ed's site in Bluewater shopping centre in Kent will relaunch under the US fried chicken concept next month.
BRG previously ran a Giraffe restaurant at Bluewater, but it closed when BRG entered into a Company Voluntary Arrangement (CVA) last year.
Slim Chickens was founded in Fayetteville, Arkansas in 2003 and has expanded to over 80 US restaurants.
BRG signed a master franchise agreement for the UK in 2018 and has since opened six restaurants in London, Cardiff, Bristol and Birmingham, with several sites replacing existing Giraffe and Ed’s restaurants.
The company expects to open further sites in key UK cities in 2020.
BRG sold fish and chip chain Harry Ramsden's to Deep Blue Restaurants late last year in order to focus on its core brands.