Saatchis' local clients, including Smartone, China Light & Power and 7-Eleven, along with about 30 staff will move into the Publicis operation at the end of October.
The current Saatchis Hong Kong management team of chief executive officer Laurie Kwong and Shaun Branagan, who has been in the executive creative director role for the past nine months, will also assume management of the enlarged Publicis Hong Kong office.
Kwong will take over from Howard Kwan, Publicis managing director, who is leaving the agency by year-end to pursue his interests in photography.
Saatchis will remain in its current premises and refocus its business to become the network's hub for its regional and international clients.
Chris Foster, currently general manager of international accounts in Asia, will head Saatchis.
Guillaume Levy-Lambert, regional chairman of Publicis Worldwide, said both agencies had been in discussion as early as seven months ago for a solution to move forward in a market that had been stagnating. "(The combining of the two agencies) is a one-off, in Hong Kong only. No one is next. There is no discussion anywhere else. Saatchis is not closing down, just refocusing (its operations to its international-networked clients)."
International clients staying at Saatchis include Guinness, Procter & Gamble, Mead Johnson and Emirates.
Levy-Lambert insisted the move was not a merger, as had happened with D'Arcy offices in Asia after the network was acquired and subsequently closed by Publicis Groupe. "(Saatchis) will have a tighter operation, more expat-style, while Publicis will have a larger operation," he explained.
Levy-Lambert said Publicis would almost double in size overnight with the integration of Saatchis' clients and staff.
Staff numbers will climb from about 50 to more than 70, and Levy-Lambert believes that Publicis - now ranked about 12th in the market - would be catapulted into the top five league after the integration.
He said the additional operational scale would allow Publicis to enhance the depth of its service offer. "I have spoken to our clients and they are very supportive because they can see that with the additional scale we will have more creative firepower, more ability to invest below-the-line," Levy-Lambert said, adding that one of the key goals would be to launch its Dialog brand in Hong Kong.
Kwong said she was excited by the development, seeing it as an opportunity to create a bigger agency with a more balanced client portfolio. "We are taking the really good people and clients from both sides to create a new and bigger agency," said Kwong.
Saatchis regional CEO Jim O'Mahony could not be reached for further comment.