Healy, who joined Walker Media in March 2011 from MediaCom, takes a new role at ZenithOptimedia that focuses on overseeing planning excellence for the worldwide network as well as ensuring that the agency's revamped positioning, "Live ROI", is rolled out across the group.
Healy will be based in London and is expected to work closely with Steve King, the ZenithOptimedia Group global chief executive.
It is understood that Healy's start date has yet to be agreed, pending the completion of negotiations with Walker Media.
Healy was hired by Walker Media as part of a restructure at the independent agency that saw Simon Davis promoted to become its chief executive.
Before joining Walker Media, Healy had been with MediaCom since 2000, working as a strategist, the head of strategic solutions and, latterly, as the head of planning, running a team of around 150 planners, strategists and econometricians. Before that, he worked as a planner and an account director at Universal McCann.
Last month, ZenithOptimedia announced that it was launching its new global positioning to reflect how digital and online media have impacted on the way consumers engage with brands.