CBS said Colbert had signed a five-year contract to helm the iconic late-night broadcast.
Colbert, 49, has been the host of Comedy Central's "The Colbert Report" since 2005.
Will Colbert remain in his Comedy Central character? Apparently not. CBS said "specific creative elements" would be determined and announced at a later date.
Colbert has been mentioned as a possible successor to Letterman for years, and his name quickly became a consensus pick after Letterman's retirement announcement on April 3. But the swiftness of the announcement was surprising.
CBS said "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."
Les Moonves, the chief executive of CBS Corporation, called Colbert "one of the most inventive and respected forces on television." He added, "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."
Comedy Central also praised Colbert on Thursday, saying: "We look forward to the next eight months of the ground-breaking Colbert Report and wish Stephen the very best."
Colbert naturally had the last laugh in Thursday's news release.
"Simply being a guest on David Letterman's show has been a highlight of my career," he stated. "I never dreamed that I would follow in his footsteps, though everyone in late night follows Dave's lead. I'm thrilled and grateful that CBS chose me. Now, if you'll excuse me, I have to go grind a gap in my front teeth."
By Brian Stelter
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