Dan Rather, one of America's most influential TV news anchors, is to leave the CBS network after 44 years.
Dan Rather complained of being sidelined at the CBS network
The award-winning journalist's last report for the network was shown last weekend, CBS said.
Rather, 74, presented the main evening news broadcast for 24 years before stepping down in March last year.
His retirement was marred by criticism of a report questioning President Bush's military service, based on evidence that turned out to be forged.
Correspondents said the incident gave ammunition to his conservative critics, who had long accused him of a liberal bias.
He stepped down from the evening news programme six months after the report aired.
Since then, he has worked as a correspondent on the magazine show 60 Minutes.
But the Texan journalist has complained of being sidelined at the network.
His contract was due to expire in November, but he was unable to come to an agreement with the network on a new deal.
CBS said it would show a retrospective documentary on Rather's career later this year.
Rather first came to attention in 1963 when, as a reporter in his home state, he covered President Kennedy's assassination.
He also interviewed President Richard Nixon during the Watergate scandal and Saddam Hussein before the US-led invasion of Iraq in 2003.
"He is truly a reporter's reporter, and he has helped to train several generations of broadcast journalists," CBS News president Sean McManus said.
"There will always be a part of Dan Rather at CBS News," he continued. "His legacy cannot be replicated."