Matthew Yeomans and Bernhard Warner join the DDB offshoot from Custom Communication, a social media consultancy established by the pair in 2006.
Before setting up the consultancy, Yeomans had written for Time, The New York Times, Wired and Travel and Leisure, while Warner had worked for a number of media organisations including Reuters, CNN and Bloomberg.
Yeomans and Warner plan to draw on this experience in their new roles of managing director and head of editorial respectively, in a bid to help clients tap into social media.
The new unit will offer a range of social media services such as brand strategy, social media monitoring and conversational branded content. Radar DDB already exists in Vancouver and Sydney, but the London office will be its first foray into Europe.
Warner will report to Yeomans, who will in turn report to the managing director of Tribal DDB, Mike Parsons.