AIB chairman Richard Pym has announced that he will retire from the bank in March of next year.
Mr Pym has been chairman of the bank since December 2014.
In a statement, AIB said after the addition of a number of recently announced non-executive directors and with a "robust succession plan" for the years ahead, Mr Pym had reviewed his commitments and concluded that it was the appropriate time to step down.
"I intend to retire in March 2020 and start a new phase of my own activities," Mr Pym said.
"It has been an honour to serve as chairman over the last five years and to work in Ireland with some amazingly talented colleagues," he added.
Colin Hunt, AIB's chief executive, said that Richard Pym has served the banking group with great distinction over the course of the past five years.
"He has used his vast pools of experience and wisdom to guide the group's development and has carried out all his duties with energy and professionalism. Under his chairmanship, the bank has gained in strength and stability and is well positioned for the challenges and opportunities that lie ahead," Mr Hunt said.
The bank said an announcement on Mr Pym's successor will be made in due course
AIB also said today that it has appointed Brendan McDonagh to the role of Deputy Chair with immediate effect.
Mr McDonagh has previously worked at HSBC and was also a director of the National Treasury Management Agency.