Stephen Colbert, host of the satirical news show The Colbert Report, is to replace David Letterman as host of CBS's Late Show, the network announced on Thursday.

CBS said Colbert would replace Letterman when he stands down from one of the most coveted slots on US television in 2015, after 21 years.

Colbert hosts his Comedy Central show in character as a spoof conservative cable news anchor. But he said that the character would end when he moves to CBS. “I won't be doing the new show in character, so we'll all get to find out how much of him was me,” Colbert said.

Letterman announced he was retiring from The Late Show on 3 April. Speculation had put Colbert in the front-runner spot to succeed him in recent days, ahead of Craig Ferguson, the Scottish comedian who hosts a show that follows Letterman. Media reports suggested Ferguson's contract with CBS means that he will get a multi-million dollar windfall if he was passed over for the job.

“Stephen Colbert is one of the most inventive and respected forces on television,” said Leslie Moonves, president and CEO of CBS. “David Letterman’s legacy and accomplishments are an incredible source of pride for all of us here, and today’s announcement speaks to our commitment of upholding what he established for CBS in late night.”

Stephen Colbert on The Late Show with David Letterman in December.

CBS said in its announcement that it reached a five-year agreement with Colbert and would announce the location of the show at a later date. “Colbert's premiere date as host of The Late Show will be announced after Mr Letterman determines a timetable for his final broadcasts in 2015,” CBS said.

Colbert has been with Comedy Central since 1997 when he started as a correspondent on The Daily Show with Jon Stewart, which he left in 2005 to create The Colbert Report (the final "t" in "report" is silent, to rhyme with Colbert). Both programmes built large audiences during the George W Bush presidency by tapping into exasperation with the Iraq war and other perceived offences out of Washington DC. The shows thrived on lampooning the mainstream media in an age when Fox News, the conservative cable news outlet, was also ascendant.

While Stewart took a relatively direct approach to criticising the Bush administration and the media, Colbert added a twist: he assumed the character of a news host with borderline chauvinist political views – a pseudo Fox News host, to many eyes. The opening credits of Colbert’s show feature a CGI bald eagle swooping over an American flag, which Colbert then grabs to plant gladiator-style in the middle of a fantasy news coliseum.

Many guests are shouted down in disagreement by Colbert playing the conservative buffoon. But the satire can be much more biting for those with whom Colbert-in-character agrees. Bush himself met that fate in a moment that more than any other elevated Colbert’s profile as an entertainer, at the 2006 White House correspondents dinner, an annual mixer of journalists and officials that Colbert was invited to host.

Standing feet away from the president, Colbert delivered a damning tribute, ironically praising Bush for the most catastrophic of his policies, from Iraq to New Orleans, then recently flooded after Hurricane Katrina. “I stand by this man because he stands for things,” Colbert said. “Not only for things, he stands on things – things like aircraft carriers and rubble and recently flooded city squares.”

The performance was greeted with shock in official Washington and among members of the press corps.

Some have suggested that Colbert would be a risky choice for CBS, a risk-averse mainstream network. But it seems unlikely that Colbert would retain his character for his new role, which requires interviewing a wide slate of celebrities on the promotional circuit. It may be that elements of The Colbert Report survive as segments on Late Night.

Key to understanding the choice may be that The Colbert Report draws about half of its nightly 1.2m viewers from the key 18-49 age group desired by advertisers. The Late Show is not as good at drawing young people, proportionally speaking, but it attracts a much larger audience, about 2.9m viewers in total. One measure of Colbert's success at CBS will be his ability to continue to attract young viewers.

The move is likely to come with a significant raise for Colbert, who made $4.5m in his Comedy Central job in 2012, according to the Los Angeles Times. Letterman's salary that year: $31m, though he took a pay cut the next year. No details of Colbert's new contract were released.

Comedy Central also recently lost The Daily Show correspondent John Oliver to HBO, where he is hosting his own show starting on 27 April.



“Comedy Central is proud that the incredibly talented Stephen Colbert has been part of our family for nearly two decades,” Comedy Central said in a statement. “We look forward to the next eight months of the ground-breaking Colbert Report and wish Stephen the very best.”