Before the appointment, Nadel was the president of Publicis Modem & Dialog in the East, based in the agency's New York office.
Her new role will now also see her assume the leadership of Publicis Modem & Dialog West, which is based in San Francisco.
She will report to Susan Gianinno, the chairman and chief executive of Publicis Worldwide in the US, and oversee a client list that includes LG Electronics, Cartier and General Mills.