The review is part of a process to consolidate the Co-op's agencies and promote it as a single brand.
It currently uses MediaCom North on its food retail and group brand campaigns, Starcom on Funeralcare and TCS North on financial services. The Co-op said it expects the new agency to be in place by the end of the year.
McCann, which had previously worked for the Co-op on brand identity and membership projects, replaces Euro RSCG London on the £15 million food ad business.
The Co-op has yet to make a decision on its Travelcare, Pharmacy and Funeralcare creative accounts, which are held by CTTG, Farm Communications and ConnectPoint respectively.
The Co-operative Bank and The Insurance Society's ad agencies, Chase, Dig Four Fire and Farm, are unaffected by the review.
