He will replace Arthur Sadoun, who was poached by the rival agency Publicis.
Pannaud is the former president of FCB France. Before that, he held a variety of roles at the agency, including strategic planner, commercial director and managing director.
As well as heading up the TBWA\Paris teams, Pannaud will also be in charge of TBWA\Interactive and Tequila.
Nicolas Bordas, the president of the TBWA\France Group, said: "We are very pleased to welcome Guillaume Pannaud. His professional reputation and know-how are well known to everyone."
