Gerry Byrne is to succeed Michael Buckley as head of AIB's Polish operations. Mr Buckley was named as chief executive designate in October last year.
Mr Byrne, currently managing director of AIB's insurance division Ark Life, takes up his new post immediately.
He also joins the group executive committee, which sets corporate strategy and oversees management of the group.
AIB's two Polish banks - WBK and Bank Zachodni - are currently in the process of merging.