Sherman, who will report to Omnicom’s chief executive and president John Wren, will be charged with driving innovation and collaboration throughout the holding company’s client accounts.
He will be one of four client-facing executive vice-presidents at Omnicom.
Sherman joins Omnicom from the WPP-owned JWT, where he looked after the North American agencies’ strategy and creative work. He joined JWT as the New York chief executive in June 2013, but was promoted to North America chief executive within six months.
Before joining JWT, Sherman was the executive vice-president and managing director of BBDO Europe, which is part of Omnicom.
Wren said: "Peter has a proven track record of effectively managing some of BBDO's largest clients and he certainly exemplifies our culture of creativity, collaboration and integrity.
"His global experience in multiple categories is perfect for the role of strengthening our relationships with our biggest clients by providing them with better and more integrated services."