Duffy, who joined AIB at the end of 2011, will take up similar position at Clydesdale Bank within the next few months.
He served as both executive director and CEO of AIB. Duffy will remain in position to support the board in identifying his successor with his final departure date to be agreed soon.
A new process will be out in place by the board to appoint a permanent successor to the role, which is subject to all relevant approvals.
AIB chairman Richard Pym said: "During David’s tenure as CEO the bank has been transformed from an organisation in difficulty to one which returned to profit in the first half of 2014 and which is well positioned to deliver on its strategic objectives to customers and shareholders.
"I will work with David in the coming period to facilitate a smooth transition and wish him every success in the future".
David Duffy said: "The bank is well positioned to contribute to Irish economic recovery and to serve customer needs.
"Having returned to profitability, received approval of the Bank’s Restructuring Plan and passed the recent ECB/EBA Comprehensive Assessment, I believe now is the right time for a new CEO to lead the bank through the next phase of its recovery and growth and a multi-year process of returning capital to the Irish State."
Image: AIB International Finance Centre in Dublin docklands. Photo: courtesy of Estoy Aquí
