Seifert, who has been with the agency for 30 years, was previously chairman, global brand community, at Ogilvy North America.
Ogilvy also announced that Bill Gray has been named vice chairman of Ogilvy North America; he had been co-CEO.
Carla Hendra, previously the other co-CEO of Ogilvy North America, continues as CEO of North America and chairman of the New York office.
Miles Young, CEO of Ogilvy & Mather Worldwide, said, “North America is our most important region. These changes provide the clarity of leadership which the new Ogilvy I envisage requires, and will allow three exceptional individuals to deploy their talents to their fullest potential.”