The French holding company plans to slot SAS into its Publicis Consultants UK group, which comprises Masius, Publicis Consultants PR and design agency Carre Noir London.
SAS specialises in corporate communications, design and interactive marketing, and generated revenues of £7.39m in 2006, placing it 16th in Marketing's league table of design agencies.
The agency employs more than 50 people and has worked for clients including Masterfoods, Sainsbury's and BT.
Publicis has appointed Jeremy Sice, the managing director of SAS, to the role of chief executive of Publicis Consultants UK. It is unclear who will take over Sice's former role.
Eric Giuily, global chief executive of Publicis Consultants, said: "Our multi-specialist network is growing fast and London is an important centre for us.
"We have been looking for some time to broaden our offer to our existing and potential clients in the UK."
Corporate adviser Results International advised on the deal.