The restaurant, on the junction of Moor Street, Old Compton Street and Greek Street, was the first Ed’s diner opened by the chain’s founder Barry Margolis in 1987.
BRG, which operates both brands in the UK, has extended the interior restaurant space to seat 34 covers under the Slim Chickens concept.
It will run a click-and-collect service, with a menu including chicken tenders, sandwiches and wings and sides such as 'Texas toast'.
Ed's was bought out of administration by BRG in 2016 with the closure of 33 of its 59 restaurants, and has 24 sites remaining.
Once converted the Soho site will be the third Slim Chickens to open in the UK since BRG signed a franchise deal to bring the US fried chicken concept across the pond last year.
BRG opened Slim Chickens in Cardiff and London’s Marylebone in 2018. The company says both sites are trading 'ahead of expectations' and it is planning to roll out the chain to other cities across the UK next year.
BigHospitality's sister site MCA reported in November that BRG had submitted plans to convert Ed’s in Liverpool to the concept.
BRG’s restaurant portfolio also includes the Giraffe, Fishworks and Harry Ramsden’s chains.