Altmann reports to Richard Pinder, chief operating officer of Publicis Worldwide. He will retain his role as the executive creative director and co-chairman at Paris-based agency Publicis Conseil.
The move is part of Publicis' plans to push the network in to the top-five most creative agencies by 2012. The most recent had Publicis at number 10 in the world.
Pinder said: "To do that I need a partner who can spend his time on global accounts and on key creative talent around our network.
"Olivier is ideal for this role having already been a chairman of our creative board and it's great to finally be able to have him in this crucial role. He will join our worldwide executive committee with immediate effect".
Altmann is charged with recruiting new talent to the network and working on Publicis' global clients Renault and Orange.