The appointment will see her assume overall responsibility for all of Univeral's US operations, including the New York, Los Angeles and San Francisco offices.
Nick Brien, the worldwide chief executive (pictured), said: "I have been impressed with Mary's strategic vision, her creative talent and her commitment to improving our business."
Gerzema joined Universal in 2003 as the communications director running the New York office. Before joining Universal, she spent seven years as the media director and general manager of the Fallon New York office.
Before that she worked at Fallon's headquarters in Minneapolis as a media strategist.