McCarthy will report directly to Susan Gianinno, chairman and CEO of Publicis Worldwide in the US, and partner with Rob Feakins, president and chief creative officer of Publicis New York, in leading the New York office.
McCarthy joins from Johnson & Johnson's global marketing group where, since 2005, he has been vice-president of worldwide advertising and marketing communications. He worked closely with all of Johnson & Johnson's creative and digital agencies worldwide including BBDO, DDB, JWT, Lowe, Deutsch and Mother, as well as many healthcare agencies such as Anderson DDB, GSW, Cline Davis Mann and CommonHealth.
McCarthy has 25 years' marketing communications experience, including 13 years at Saatchi & Saatchi New York, where he started his career before moving to Nike in 1993 as head of global advertising.
He was also CEO and founding partner of McCarthy Mambro Bertino in Boston in 2001, which still bears his name and has worked with clients including Subway, Sam Adams and ESPN.
McCarthy said: "This is a fantastic opportunity for me to partner with Rob and Dani [Nadel, president of Publicis Modem and Dialog East] to further build the Publicis agency brand and its creative culture into the most relevant, idea oriented, and integrated offering.
"I have a pretty good feel and perspective for what is missing in today's market from a client perspective. There's a lot of talk about the future. It is time to stop talking and act now."
McCarthy will begin his new role on August 18 and will join Feakins as a member of the Publicis USA leadership team and the Publicis Worldwide management council.
Duff was president and CEO of Publicis New York for the past four years. Publicis said that he made a personal decision to move from agency office management to his "real passion, which is deeper, more-focused client management responsibility".
The agency said that it is in discussions with Duff about a major client assignment in the Publicis Groupe.
Gianinno said: "Publicis in New York has to be our strongest office... the one that epitomises who we are and what we offer. The CEO and chief creative officer of Publicis in New York must have all it takes to lead a creatively driven, digitally savvy, client attuned operation. Joe and Rob together are perfect partners to deliver this for Publicis."