"This brutal ordeal is now officially over, and I will never speak of it again," he said on his talk show, "The O'Reilly Factor."
Andrea Mackris, 33, who was a producer on the show, filed a lawsuit against the top-rated TV host Oct. 13, alleging O'Reilly made a series of explicit phone calls to her, advised her to use a vibrator and told her about sexual fantasies involving her.
The New York Daily News, citing unidentified sources, reported that O'Reilly had agreed to pay Mackris anywhere from $2 million to $10 million. Separately, the New York Post said it was believed that O'Reilly paid "multimillions of dollars" to settle the suit.
Earlier that day, O'Reilly, 55 and married with two children, had filed a lawsuit accusing Mackris and her lawyer of trying to extort $60 million in "hush money" to make the case quietly go away.
O'Reilly is host of the top-rated prime-time cable news program -— and he's seen his ratings go up by 30 percent since the case was filed.
The out-of-court settlement came on the eve of a courtroom fight over audiotapes, reports CBS News Correspondent Kelly Cobiella.
O'Reilly lawyer Ronald Green had said he believed there were tapes of conversations between the two and asked a court to compel Mackris to produce them so they could be played publicly.
"I know that he does not fear what is on the tapes," Green said at the time.
O'Reilly told his viewers Thursday night, "This matter has caused enormous pain, but I had to protect my family, and I did. All I can say to you is please do not believe everything you hear and read."
Shortly before "Factor" aired, O'Reilly's lawyer Green, issued a statement saying the cases and claims had been withdrawn and all parties agreed there was no wrongdoing by O'Reilly, Mackris or Mackris' lawyer Benedict Morelli.
Morelli did not immediately return a telephone call seeking comment.
Green's statement about the settlement did not mention money, and it could not be learned immediately whether it was a factor.
"Out of respect for their families and privacy, all parties and their representatives have agreed that all information relating to the cases shall remain confidential," Green's statement said.
When the accusations began, Green refused to confirm or deny specific things that Mackris claimed O'Reilly said to her, but he said at the time that, "Mr. O'Reilly denies that he has done anything that rises to the level of unlawful sexual harassment."