The branch at 19-21 Cornmarket in Belfast was the best performer of all Leeds’ 67 branches.
Trevor Garside, head of direct distribution at Leeds Building Society, said: "I am delighted to announce that our 2014 branch of the year is Belfast.
“Ian Devany, Belfast branch manager, had a vision in 2014 which he executed effectively and this has produced a fantastic set of results.
“We look for the branch which is relentless in their desire to deliver on all fronts, and the team in Belfast are outstanding examples of this and show a real focus to succeed.”
