The appointment of Havas Media's global sports and entertainment communication network ends a 14-month pitch process in which it called upon the expertise of its group agencies Euro RSCG, Mégaphone Team, Altius Prod and Havas Media's MPG.
The decision was made by France's Annecy 2018 association, which was created in June 2009 to present the city's candidacy to host of the 2018 winter events.
The Havas network will now play a pivotal role in communicating and implementing the ideas behind France's Olympic bid as it battles against rival cities Munich (Germany) and PyeongChang (South Korea).
Gilles Portelle, general director of Havas Sports & Entertainment France, said he was "proud" to be representing France and pledged to "mobilise the strength of our entire international network to the success of this major international sporting bid".
Havas Sports & Entertainment consists of 400 professionals operating globally through 20 offices.
Included among its international portfolio of clients are Coca-Cola, adidas, McDonald's, Allianz and Mars.