Eric Schmidt, Google's chief executive, said "possibly hundreds" of Google employees could take placements within Publicis, which owns Saatchi & Saatchi and Fallon, digital specialist Digitas, and media shops ZenithOptimedia, Zed and Starcom.
Publicis' stance of treating Google as a partner contrasts with the attitude evinced by WPP Group chief executive Sir Martin Sorrell last April when he described the search giant as a "short-term friend and a long-term enemy".
Sorrell said this after Google bid for internet display advertising network DoubleClick, and only weeks before WPP bought similar network 24/7 Real Media.
While Sorrell may believe Google is seeking to take over advertising groups' territory, Maurice Levy, the Publicis chief executive, is inviting the US company across his doorstep.
Levy said: "Google is not a short-term friend and a long-term enemy. It's a real partner.
"The world of advertising has to change. That is what we are building for tomorrow. The partnership with Google is not about creating one product. It is about creating a concept that will work across our whole company."
"We are sharing our information to help Google develop the right platforms and Google is sharing technology to help us develop the best services for our clients."
Schmidt told journalists yesterday: "Google will never become an advertising agency."