The French-owned FMCG company pitched its UK dairy and water brands, including Actimel, Evian and Volvic, as part of the process.
The pitch started in July, with presentations taking place in September. The review is part of a global process that started last year and ends in 2008, with decisions being made at a local level.
Gayle Noah, Danone UK media manager, said: "All four agencies exhibited a high level of competence and professionalism, but it was MEC who demonstrated a deep understanding of our brands, creativity and strategic insight into how we can navigate the challenges ahead. In addition, they showed us they can add real value through strong media performance and ROI.
"We look forward to working with MEC as we move into the next stage of Danone's development in the UK."
Tom George, managing director of MEC, said: "It goes without saying that we're delighted to have been appointed by Danone to handle their business in the UK, and to emerge victorious after a really challenging brief is testament to the quality of the people and their thinking at MEC.
"The opportunity to work with some of the biggest and best brands in the sector is really exciting and we can't wait to get started."
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