The four-strong account team is headed by Spin Media MD Andy Spinoza.
He said the agency's work would include consumer work in addition to corporate profile-raising.
'As well as coverage of deals, we're looking at a number of events at which they can raise their profile,' he said.
Spinoza added that the agency would be covering community issues-related work, supporting the client's key message of 'relationship banking'.
The account was won following a pitch against three Manchester-based agencies, after a four-month review process.
The PR review was overseen by Co-operative Bank head of corporate and business banking Bryce Glover, to whom the agency reports.