Mr. Schmetterer has been chairman-CEO of Havas' Euro RSCG Worldwide for the past six years, a position he will retain while assuming his new responsibilities.
He and Alain de Pouzilhac, Havas' chairman-CEO, will manage the holding company together.
In a statement, Mr. Pouzilhac said: "I've known Bob for a long time and we have developed a strong friendship and trust. We share the same values, the same vision and view of our times and we have the same ambition for Havas."
Havas owns agency networks Euro RSCG MVBMS and Partners, Euro RSCG Tatham Partners and Arnold Worldwide, among other shops.