Hytner will take over the strategic role from Dundas, who is leaving the agency after seven years.
Dundas said his reasons for stepping down were that after 20 years in the industry and the constant travelling, it was time for a break.
Based in London, Hytner was previously chairman and chief executive officer for the agency's offices in Europe, the Middle East and Africa.
The Manchester-born law graduate joined the industry 20 years ago, starting in media planning. He went on to run the merged Still Price Court Twivy D'Souza-Lintas agency at the age of 32 and chair the WPP-owned market research group, the Henley Centre. He was also chief executive of Ammirati Puris Lintas and Publicis London.
The EMEA duties will be handed over to Jim O'Mahony, the New York-based chief executive for Asia, Australia and Latin America since March 2004. He now becomes chief executive for EMEA, Asia and Latin America.
O'Mahony and Hytner will continue to report to Kevin Roberts, Saatchis global chief executive.
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