Jimmy Fallon said he was "just as shocked as everyone" and Seth Meyers called him a great host and comedian but an even better person.
John Oliver said he was excited to see what Colbert and his team would do during the final 10 months of the program.
Jimmy Kimmel directed an expletive at CBS, and Andy Cohen said it was a sad day for the network.
As for US President Donald Trump - a frequent target of Colbert's comedy - he said on Truth Social that "I absolutely love" that Colbert was "fired".
Some of the reaction from the late-night world:
JOHN OLIVER
* "I love Stephen, I love his staff. I love that show. It's incredibly sad. I am partly excited to see what they're going to do for the next 10 months. It's terrible, terrible news for the world of comedy. Late-night shows mean a lot to me, not just because I work in them, but because even growing up in England, I would watch Letterman's show, which of course was Stephen's show, and think about what a glamorous world that was. So to have got to be on Letterman's show and Stephen's show has been always one of the most fun things, so it's very, very, very sad news. I look forward to seeing what he's going to do next because that man will not stop." - the HBO Last Week Tonight host during an appearance in Erie, Pennsylvania, on Saturday.
JIMMY FALLON
* "I'm just as shocked as everyone. Stephen is one of the sharpest, funniest hosts to ever do it. I really thought I'd ride this out with him for years to come. I'm sad that my family and friends will need a new show to watch every night at 11.30." - the NBC Tonight Show host, on Instagram
SETH MEYERS
* "For as great a comedian and host (as) he is, @stephenathome is an even better person. I'm going to miss having him on TV every night but I'm excited he can no longer use the excuse that he's 'too busy to hang out' with me." - the NBC Late Night host, on Instagram
JIMMY KIMMEL
"Love you Stephen." - the Jimmy Kimmel Live! host, on Instagram
ANDY COHEN
"It is a very sad day for CBS that they are getting out of the late-night race. I mean, they are turning off the lights after the news." - the Watch What Happens Live host, in an interview
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