Denney takes the reins back from former Typing Room head chef Greg Clarke, who is now in Hong Kong.
Clarke and his team left 108 Garage abruptly at the start of this week.
A spokesperson for the restaurant says the departure was amicable in nature, although BigHospitality understands that this may not be the case.
The restaurant was launched in 2016 by Luca Longobardi and Chris Denney. Denney stood back from the kitchen a month ago to focus on the wider business.
The opening of 108 Garage was followed by Southam Street restaurant, a three-storey restaurant in a former pub down the road, which launched last year.
Longobardi and Denney now have several projects in the pipeline together, including Home Noir, a members’ club with 20 loft apartments, restaurant, clubhouse and roof deck.