The brief covers planning for all consumer communications, including advertising, direct mail, and in-store activity for all the brands in Masterfoods' three divisions.
The decision means MediaCom adds brands such as Mars Bar, M&Ms, Whiskas, Uncle Ben's and Dolmio to the Pedigree, Twix, Galaxy and Milky Way accounts it already handles.
Paul Smith, regional media manager for Western Europe, said MediaCom won the business by demonstrating an "excellent understanding of our business and our target audiences and showing absolute dedication to optimising our consumer communication strategies".
Previously, MediaCom shared the UK planning roster with MediaVest and PHD. It pitched against Zenith Optimedia Group, Starcom MediaVest Group, PHD and Media Planning Group.