Incumbent agency FCB London declined to repitch for the work after the review was announced by new Weetabix chief executive Ken Wood.
FCB was appointed to the account in November 2001, taking over from Lowe, which created the iconic "Withabix/Withoutabix" advertising.
Wood joined Weetabix in the summer from the Muller Group, and his arrival was followed by the sudden departure of commercial director Bill Humes.
DDB will start work on the account immediately with a brief to support the entire Weetabix cereal portfolio, including Weetabix, Weetabix Minis, Alpen, Ready Brek and Weetos.
Paul Hammersley, chairman and chief executive at DDB London, said: "Weetabix is a genuinely iconic British brand that any agency would kill to have on its roster. It is also the kind of brand for whom this agency has always produced exceptional work."
He added: "It is positively exciting to be working with Weetabix's new owners and new management as they start to move the business forward."
DDB London takes over the account at a time when Weetabix sales are riding high. In 2002, it overtook Kellogg's Corn Flakes as the UK's biggest cereal brand with advertising under the theme "Generating energy for everyone".
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