Writers, actors and prominent Democrats have condemned Kimmel's suspension.
Former US President Barrack Obama said the Trump administration had taken cancel culture to a "new and dangerous level by routinely threatening regulatory action against media companies unless they muzzle or fire reporters and commentators it doesn't like".
Late-night show hosts have rallied around Kimmel.
In a rare mid-week episode of The Daily Show, comedian Jon Stewart poked fun at the curtailing of free speech under the current administration.
Stewart described himself as a "patriotically obedient host" and his programme as "administration-compliant". He then referred to Trump as "dear leader" who has been "gracing England with his legendary warmth and radiance".
In a later segment of his show, Stewart interviewed Maria Ressa, who was awarded the Nobel Peace Prize in 2021 for her fight for free speech and democracy in the Philippines under former President Rodrigo Duterte.
What's happening in the US is "identical to what happened in the Philippines," Ressa said. "It's both deja vu and PTSD."
She added: "Americans are like deer in headlights. If you don't move and protect the rights you have, you lose them, and it's so much harder to reclaim them," she said.
Actor Ben Stiller said what happened to Kimmel "isn't right", while Hacks star Jean Smart said she was "horrified at the cancellation".
The Writers Guild of America and Screen Actors Guild, two Hollywood trade unions, condemned the suspension of Kimmel as a violation of constitutional free speech rights.
But others have maintained the FCC and ABC acted appropriately.
"When a person says something that a ton of people find offensive, rude, dumb in real time and then that person is punished for it, that's not cancel culture," said Dave Portnoy, who founded media company Barstool Sports.
"That is consequences for your actions."
Late-night Fox host Greg Gutfeld argued that Kimmel had "deliberately and misleadingly" blamed Kirk's "allies and friends" for his death.
British presenter Piers Morgan said Kimmel had caused "understandable outrage all over America", adding: "Why is he being heralded as some kind of free speech martyr?"
But one of Carr's FCC leadership colleagues, commissioner Anna Gomez, a Democrat, criticised the regulator's stance.
She said that "an inexcusable act of political violence by one disturbed individual must never be exploited as justification for broader censorship or control".