General Secretary of the Irish Congress of Trade Unions David Begg is to retire from his position in March.
Mr Begg has held the position since 2001.
He previously worked for the ESB Officers' Association and the Communications Workers' Union.
From 1997 to 2001, he was CEO of the international charity Concern Worldwide before taking up his current position with ICTU.
He is a member of the National Economic and Social Council and a non-executive director of Aer Lingus.
Mr Begg previously served as a director of the Central Bank and as a governor of the Irish Times.
At the last ICTU conference in Belfast in 2013, Mr Begg indicated that he would be stepping down before the 2015 conference, but did not indicate a precise time frame.
He was a key union negotiator in a number of social partnership agreements.
Mr Begg made his announcement at the ICTU Executive Council meeting this morning.