The 67-year-old, who founded the Cable News Network in 1980 and merged his company Turner Broadcasting with Time Warner in 1995, will leave the board in May instead of standing for re-election.
He said, "It is after much deliberation that I have decided not to stand for re-election at the annual meeting.
"I have enjoyed working with (TW chairman and CEO) Dick Parsons, as well as the other board members and the management team.
"I wish Dick and the company every success."
Parsons paid tribute to Turner's career, saying, "He is a visionary leader who has made an extraordinary contribution to this company and, indeed, to the world at large."
A spokesman explained the billionaire and ex-husband of actress Jane Fonda plans to focus his attention on philanthropic projects and his growing restaurant business.