Benson was previously at MindShare Worldwide, where he was the managing partner on the European Ford account.
His appointment is the first made by ZenithOptimedia's new global chief executive, Steve King, and is intended to improve its strategic planning at international level.
Based at ZenithOptimedia's London HQ, Benson's role will see him working closely with the agency's global clients and taking responsibility for the management and training of local planning managers.
Before joining MindShare, Benson worked at Motive on its Levi's and Heineken accounts and at McCann Erickson on Coca-Cola.
King said: "I want to focus more on the product -- strategic resources, research and particularly communications planning. I needed to bring in the most heavyweight person I could."
Benson said: "I am excited by the changes going on at ZenithOptimedia. I believe that its support of the ROI philosophy has tremendous potential."
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