He told his audience he expects his departure will be "at least a year or so" from now.
It appears the end is near for Late Show host David Letterman.
Reports started circulating Thursday afternoon on Twitter the host of the Late Show with David Letterman would be retiring in 2015, when his current contract expires.
Former REM bassist Mike Mills posted on his Twitter account that Dave made the announcement while taping Thursday night's show. Mills was there to perform with the night's musical guest, Joseph Arthur.
CBS Evening News Sunday Correspondent Jeff Glor also confirmed the announcement on his Twitter feed. He said CBS will have more on Dave's announcement on tonight's CBS Evening News.
Letterman turns 67 next week. This year marked David Letterman's 30th year in late-night comedy and, in August, will mark his 19th year as the host of the Late Show with David Letterman on CBS, according to CBS.com.
"It's going to be tough to say goodbye," CBS President and CEO Les Moonves said in a statement. "Fortunately, we won't have to do that for another year or so."
Jay Leno, his rival to host NBC's "Tonight Show," retired earlier this year, making way for Jimmy Fallon.
The following statement was released by Letterman on Thursday afternoon:
David Letterman, during a taping of tonight's Late Show, said that he informed Leslie Moonves, President and CEO of CBS Corporation, that he will step down as the host of the show in 2015, which is when his current contract expires.
"The man who owns this network, Leslie Moonves, he and I have had a relationship for years and years and years, and we have had this conversation in the past, and we agreed that we would work together on this circumstance and the timing of this circumstance. And I phoned him just before the program, and I said 'Leslie, it's been great, you've been great, and the network has been great, but I'm retiring,'" said Letterman.
"I just want to reiterate my thanks for the support from the network, all of the people who have worked here, all of the people in the theater, all the people on the staff, everybody at home, thank you very much. What this means now, is that Paul and I can be married."
"We don't have the timetable for this precisely down – I think it will be at least a year or so, but sometime in the not too distant future, 2015 for the love of God, in fact, Paul and I will be wrapping things up," he added, to a standing ovation from the audience in the Ed Sullivan Theater.
Letterman's career as a late night broadcaster has spanned more than 32 years and nearly 6,000 episodes. He was the first host of Late Night at NBC from 1982-1992, and he has been the only host of Late Show, which he created on CBS in 1993. The two shows have been nominated for 108 Emmys, winning eight. Late Night received a Peabody in 1992, and Letterman became a Kennedy Center Honoree in 2012.
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The Associated Press contributed to this report.