Other Coca-Cola-owned businesses in the UK, including the Nestea and Minute Maid brands, are held by Vizeum and are unaffected.
The remit will cover digital, TV and outdoor. Last year, CCE's Appletiser signed a £1m deal with Channel 4 to sponsor re-runs of hit series Friends.
Mediaedge:cia holds the global media account for Sab Miller, whose brands include Appletiser.
Industry sources said that CCE had become increasingly demanding of its media as it gears up for new launches. The spend attached to the brief made it difficult for Walker to meet those demands.
Walker opted to rescind the account at a time when it was focused on internal digital repositioning, after capturing the £70m Barclays brief earlier this year.