The win marks the first time that Ribena will have an agency operating at a global level. Previously, Ribena worked with various agencies across the world at country level, and these agencies will continue to work on local projects.
The global brief excludes the UK and Ireland, as that part of the business remains with M&C Saatchi, which won the account from Grey London in 2005.
Grey London picked up the account after working on Ribena’s brand stablemate Lucozade for the past three years.
Ribena’s media buying and planning has not been consolidated into a single agency, and will continue to be serviced by agencies locally.
Grey’s first work as Ribena’s global ad agency is expected in March 2014. The agency previously created the brand’s "berry" characters in the 1980s.
The London office of Grey was appointed to Lucozade’s ad account in 2010 after a competitive pitch, beating the incumbent, M&C Saatchi.
In September 2013, Japanese company Suntory bought Lucozade and Ribena from GlaxoSmithKline for £1.35 billion.
Jon Roberts, Ribena and Lucozade’s international marketing director said: "Through their work over the past three years for Lucozade, Grey London has shown considerable energy, eye-catching creative and understanding of the international drinks category.
"I really look forward to this work being activated in markets in Africa and Asia, driving a closer consumer connection with Ribena."