Octopus will handle the wide-ranging brief, which also includes events and design, as the banking body nears a deadline for compliance with EU law on Single Euro Payments Area (SEPA), an EU initiative governing bank transfers.
The EPC, which is responsible for developing payment frameworks across the region, held a multi-agency pitch.
Iseepr previously handled a number of comms functions for EPC, but split amicably with the body at the end of last year due to a change in the scope of the comms brief.
Octopus will communicate EPC and SEPA developments to stakeholders, including payment service providers and wider business, through media relations campaigns and social media activity.
EPC comms manager Meral Ruesing said: 'The SEPA process is at a crucial stage, with less than a year to go until market participants in Europe must meet the 1 February 2014 deadline for SEPA compliance mandated by EU law.'