Johnson, who held the same position at Rapier, will work on campaigns for Mercedes-Benz, 3, Egg and ING Direct, and will report directly to Xavier Rees, deputy managing director.
Johnson is a former analysis director at Proximity, where he was responsible for customer marketing and acquisition for Virgin Media, and also led data planning for the Barnardos, COI and Digital UK accounts. Prior to this, Johnson was head of insight at eBay.
Rees said: "His wealth of experience on both sides of the client agency spectrum will be an immense asset to the agency."
In January, the agency made five senior appointments across its digital creative business, including Alex Comyn for account director, Ben Garraud as creative technologist, and Michael Burgon and Simon Brown as senior designers.