The newly-formed Co-operative Financial Services (CFS) will promote cross-selling between the Co-operative Insurance Society (CIS) and the Co-operative Bank.
CIS chief operating officer Finian O'Boyle said the CIS had historically operated quite independently from the bank, despite being part of the same group.
"There was little overlap between banking and insurance," he said. "CFS will bring them closer." He said cross-selling had "huge potential".
O'Boyle said CFS's advantage was that it had a full product range, spanning the banking and insurance arms.
"We have the leading home sales force in insurance and the bank is a leading direct banker through the telephone and internet," he said.
"We now have to think carefully about the sorts of customers we have and which ways they would prefer to talk to us."