The scandal, which was initially reported by The New York Times, had motivated about 50 companies - including big names such as Mercedes-Benz, Hundai and BMW - to withdraw their advertising from "The O'Reilly Factor", the host's evening programme.
Perino said at the top of the show that, "We know you, his loyal viewers, will have a lot of feelings about it".
Both Fox and O'Reilly confirmed O'Reilly's departure from the network earlier Wednesday. O'Reilly has maintained his innocence.
Activist groups such as the National Organisation for Women have been bringing pressure to bear for weeks on the firm to fire O'Reilly in a case that NOW said became emblematic of the "culture of sexual harassment at Fox News" and requires an "immediate independent investigation".
In a statement Wednesday, the channel confirmed that the TV adaptation is in early development for 2019.
In addition to hosting "The Factor", O'Reilly has also written a series of historical narratives, including "Killing Jesus" and "Killing Lincoln", that have each sold more than 1 million copies in hardcover.
Fox News announced that it was working with advertisers, shifting their buys to run on other shows. He commented on the issue Wednesday, calling it "tremendously disheartening" and labeling the claims "completely unfounded", according to the Washington Post.
Yet the allegations against O'Reilly fit into an uncomfortable narrative for the cable news network. He thanked his viewers and noted the success Fox had achieved.
O'Reilly's departure follows the ouster of Fox News' former chief Roger Ailes, a close confidante of the company's founder Rupert Murdoch, also over sexual harassment charges. It had previously aired at 9 p.m.
At 7 p.m. EDT, Martha MacCullum remains in place.
Rounding out the Fox prime-time lineup, "Hannity" remains at 10 p.m. EDT.
Bill O'Reilly has lost his job at Fox News Channel following reports that five women had been paid millions of dollars to keep quiet about harassment allegations.
Fired on Wednesday amid a drumbeat of sexual harassment allegations, the vacationing host's "The O'Reilly Factor" was quickly redubbed "The Factor" and Fox News announced his time slot will be filled by Tucker Carlson, another adamantly conservative Fox host who dovetails with the channel's audience.
It marks a stunning end to a near ideal marriage between a pugnacious personality and network. "Bill has been the undisputed king of cable news, and for good reason".
Francis always swings by the VIP seats at the end of his audience for a quick round of handshakes.
"Getting rid of the old guard is a way to do that", said Dan Cassino, a professor at Fairleigh Dickinson University and the author of "Fox News & American Politics: How One Channel Shapes American Politics & Society". On Tuesday, the Wall Street Journal, a newspaper owned by the Murdochs, wrote that the company was preparing to cut ties with O'Reilly.
O'Reilly has been enmeshed in controversy since the start of this month after The New York Times reported five women were paid about $US13 million ($A17 million) in exchange for agreeing not to pursue litigation or speak about the accusations.
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