Inferno founding partner and CEO Frazer Gibney will run the combined agency, with Inferno founding partner Tim Doust and chief creative officer Al Young retaining their roles post-deal.
The merger includes the departure of Kate Howe, DraftFCB’s London president and regional European president, and David Harris, creative director of the agency.
The newly merged company is understood to have been in discussion for more than a year and will initially be called Inferno & DraftFCB. A new management structure will be announced next month.
Inferno counts among its clients broadcaster BSkyB, online platform Skype and mobile phone company Nokia.
Carter Murray, worldwide CEO of DraftFCB who joined the agency in September from Y&R North America, said: "Inferno and DraftFCB’s combined capabilities and instant critical mass will enable the agency to better service global clients and grow more quickly organically."
Gibney said: "The merger with DraftFCB’s UK office creates an agency with enhanced capabilities globally and locally. It’s a natural next step for an agency with global ambitions to join a premier league network."
He added that the deal would "now enable the agency to deploy globally".