Off-camera unseen forces raged against him, culminating in Fox News Channel's admission today that O'Reilly is getting the boot.
Mr O'Reilly, 67, had hosted the show from its inception in 1996.
O'Reilly will be replaced in the coveted 8 p.m. ET time slot by Tucker Carlson, NPR reported.
He said he was proud of what he termed "one of the most successful news programs in history", thanked his viewers and wished "only the best" for Fox News.
In a nod to the allegations against O'Reilly, the statement closed with "we want to underscore our consistent commitment to fostering a work environment built on the values of trust and respect".
Then, she said, she complained to Ailes, who resigned from the network past year amid allegations of sexual harassment. He thanked his viewers and noted the success Fox had achieved.
Still, the substitutes beat their cable news competition.
So what changed? Was it lurid details of his alleged behaviour?
All eyes will now focus on O'Reilly's replacement.
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Before Conservative Gasbag Colbert paid tribute to his fallen hero, Actual Colbert also addressed 21st Century Fox's announcement it was parting ways with O'Reilly amid mounting allegations of sexual harassment and inappropriate behavior.
And 21st Century Fox is much bigger than O'Reilly, Fox News and its aging, conservative audience.
When the Murdochs went the other way, O'Reilly prepared a statement with the help of his agents and crisis communications adviser.
His exit will be a far greater blow than the departure of rising star Megyn Kelly.
O'Reilly averaged almost 4 million viewers a night for the first three months of 2017, his best performance ever. As we mentioned earlier, Bill O'Reilly is leaving this chair and this network after more than 20 years.
Powers said she had learned to tolerate behavior like this. "He would always do this when no-one else was around, and she was scared".
The network's parent company, entertainment giant 21st Century Fox, insisted that Fox News will weather the current storm, noting in a statement the "strength of its talent bench" and expressing "full confidence that the network will continue to be a powerhouse in cable news".
A concern for the Murdoch family is their pending $14bn (£11bn) deal to buy out satellite provider Sky, which is being scrutinised by British regulators.
Sources at the company tell U.S. media that Rupert Murdoch was in favour of keeping Mr O'Reilly in his post.
Media mogul Rupert Murdoch and his son Lachlan are co-executive chairmen of the company and son James is chief executive officer. Burke, a former Fox News correspondent in Rome, denied having facilitated the tickets.