Barrett Cernis has won the Ame account, joining HHCL & Partners, Abbott Mead Vickers BBDO and Burkitt DDB on the Britvic roster.
Britvic acquired Ame in July when the drinks giant purchased Orchid Drinks, a stable of brands that include Aqua Libra and Purdeys.
Andrew Marsden, the Britvic category director, said: 'Ame is an important acquisition for us and an exciting brand to be working on. We're looking forward to getting some innovative advertising from the Barrett Cernis team.'
Barrett Cernis is developing a strategy for the brand and creative work is expected to appear early next year.
The last major campaign for Ame was created four years ago by Cowan Kemsley Taylor. It positioned the brand as an alternative to wine at dinner parties.
Justin Cernis, the managing director of Barrett Cernis, said: 'Britvic is a coveted roster because the client is brave. If we can get this first task right, we hope more work will follow. I am convinced we'll produce work that will maintain the Britvic tradition of outstanding creativity.'
Media for all Britvic brands is centralised at MindShare. Britvic's portfolio includes Pepsi, Tango, 7-Up, Robinsons and Ballygowan.