He is stepping down as the executive chairman of PublicisLive in order to pursue "entrepreneurial opportunities outside the Groupe".
The Morocco-born Attias founded PublicisLive, a Geneva-based agency that specialises in producing international conferences.
He married Cecilia Ciganer-Albeniz in March at a ceremony in New York's Rockefeller Center.
John Rossant, the Publicis vice-president of communications and public affairs, will become the new executive chairman of PublicisLive.