The group acquired supermarket chain Somerfield last month for £1.6bn. Somerfield's media business is currently handled by full service agency WWAV Rapp Collins. Co-op's food and banking business is held by PHD.
Other agencies working with the group include MediaCom North and Brilliant Media.
Businesses included in the review include Co-op Travelcare, Co-op Travel, Co-op Insurance Society, Co-op Bank, Co-op Funeralcare, Priority Motor Group, Unity Trust Bank, Co-op Group and Co-op Financial Services, which counts internet bank Smile among its brands.
Somerfield spent £12m on media in 2008 while the Co-operative Group spent a total of £42.4m, according to The Nielsen Company.