When asked about the review, Alison Jones, Co-op's newly appointed customer director said: "We regularly review agency support to ensure we get the best support, which meets our strategic aims."
The review, she continued, is aimed at consolidating the brand's media agency buying and planning services.
"A pitch will be held soon with support from our partner, Media Sense. As a member-owned business we always seek value for money to help build a stronger Co-op."
Hearts & Science picked up the account when Omnicom merged its media agency Rocket with Hearts & Science in January this year.
Rocket has held the account for more than a decade, picking up the then £10m account in 2006.
Since then it has retained the retailer's account through several reviews, including in 2012 when the account was valued at £50m.
Co-op's creative agency of record is Forever Beta.