Jerry Levin, the CEO of AOL Time Warner, is to retire in May next year.
The move is part of a decision to streamline the giant media company's management structure.
Richard Parsons, currently co-COO with Robert Pittman, will replace Mr Levin as CEO.
Mr Pitman will become the sole COO at the company.
Steve Case will continue as chairman.
Said Mr Levin: "This is a step that I have been thinking about for some time and whose time has come.
"Given that we are almost a full year into the merger and that an outstanding management team is now in place at the company, I am convinced that AOL Time Warner should begin an orderly transition to a new era of leadership."
Mr Levin has spent almost all his career at the company after graduating from law school in the early 1960s. ®