The agency, which won the business without a pitch, will work on an above-the-line campaign to be released at the end of the year.
Ready Brek, which usually advertises on a seasonal basis, was last supported by a major ad campaign in 2009.
TV advertising, by WCRS, showed a young boy surrounded by the Ready Brek "glow" eating the porridge before setting out for his school day.
The Ready Brek glow was part of the memorable "central heating for kids" work that ran throughout the 70s, 80s and 90s.
In 2006, Weetabix relaunched Ready Brek to be promoted as a porridge oat cereal that can be eaten throughout the year. WCRS revived the glow in 2008.