"I have to start by addressing a well-orchestrated effort by the intolerant left in this country that is designed to silence every conservative voice and by any means necessary," Hannity said during his monologue.
"Now, I'm speaking out tonight so that you, our audience, will understand what is really happening and what is at stake when it comes to freedom of speech in this country."
Hannity said there have always been efforts during his time at Fox News to "smear and slander and besmirch" him. But those efforts have not been as "intense and completely insane" as they are now, he added.
"It has only gotten worse in the age of President Trump," Hannity said.
"Now, it's no secret I have been a supporter of the president and of course his policies. And quite simply, these liberal fascists — they can't stand conservative voices."