"Of all the famous names associated with CBS News, the biggest and the brightest on the marquee are Murrow, Cronkite and Rather," CBS News and Sports president Sean McManus said of Rather's 44 years as a reporter and news anchor.
However, Rather, 74, made it clear the break was not his choice.
He did not participate in Wednesday's announcement and refused to be interviewed.
"My departure before the term of my contract represents CBS' final acknowledgement, after a protracted struggle, that they have not lived up to their obligation to allow me to do substantive work there," he said.
"As for their offers of a future with only an office but no assignments, it just isn't me to sit around doing nothing," he said. "So I will do the work that I love elsewhere, and I look forward to sharing details about that soon."
Rather reportedly was considering an offer to anchor a documentary series for HDNet, a high-definition cable television channel.