Chambers, who will report to the UK chief executive, Chris Mellish, has been working as a freelance creative director on the agency's Lynx account.
Before that, he was a creative director at the digital agency Blast Radius Europe and a strategy director at Tribal DDB Europe. He has also worked at Poke and Euro RSCG, and co-founded the digital shops Kong in Amsterdam and Double Denim in Stockholm.
Separately, the Publicis-owned agency has promoted John Cunningham, the former head of technology for Razorfish UK, to chief technical officer, Europe.
He will head up a team of more than 80 people to ensure that a strong technology offering underpins the agency's creative solutions.
The appointments follow last year's hirings of Daniel Bonner and William Lidstone as the chief creative officer, Europe, and executive vice-president, Europe respectively.
Mellish said: "Sean personifies our philosophy of putting innovation and creativity at the core of all we do."