The two hosts shall meet.
The news comes just days after CBS announced that "The Colbert Report" host will succeed Letterman next year.
Earlier this month, Letterman, 67, announced that he would retire in 2015. Specifics about when he will officially step down have not been announced.
Colbert, 49, has been a guest on Letterman's show before, and pretty soon he'll start welcoming his own string of late-night guests. He will portray himself on the "Late Show" -- not his Comedy Central character. There's still no word on where the show will tape.