Priorities for EHS Brann, which has already worked with Barclaycard on a series of projects, will be to focus on the key European markets of Spain, Germany and Italy and across the continent capitalise on the brand's link with Barclays.
EHS Brann has also been hired to help Barclaycard gain a foothold in new markets in Asia, India and Africa.
Globally the agency is to develop a toolkit for Barclaycard's network of local agencies to use.
Richard Harvey, European marketing director at Barclaycard International, said: "The focus is very much on growth for us and to penetrate these markets successfully we recognised that we needed a central strategic agency which could coordinate our marketing activity and ensure we weren't starting from scratch each time."
As part of the deal, EHS Brann Group's data division EHS Brann Discovery will handle data planning and identifying customer segments.
Matt Atkinson, EHS Brann chief executive officer, added: "The challenge will be to help create consistency and relevance for Barclaycard in these markets, while developing a customer centric approach."
The appointment comes as EHS Brann faces two reviews for its Peugeot Citroen account and the British Heart Foundation.
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