Gervaise Slowey has resigned as chief executive of Denis O'Brien's Communicorp Group.
The company said that Ms Slowey will be replaced by Adrian Serle, the former chief executive of the UK media company, Orion Media.
In a statement, Communicorp said Ms Slowey will continue in her role until the end of the year when Adrian will take up the position.
"After four exciting, fast paced and thoroughly enjoyable years, I believe my time here has come to a natural end," Gervaise Slowey said in today's statement.
"Communicorp is made up of a strong dynamic team of incredibly brilliant people across all the businesses and functions who have been truly inspirational to work with. I would like to thank Lucy Gaffney, the board and the management team for the opportunity and support over the years and I wish them every success as they embark on the next phase," she added.
Communicorp owns a number of radio stations in Ireland, including Newstalk, Today FM, and Dublin's 98FM as well as several in the UK.