Conservative megastar talk show host Bill O'Reilly has been dropped from the Fox News Channel lineup following an investigation into allegations of sexual harassment, 21st Century Fox said Wednesday.

“After a thorough and careful review of the allegations, the Company and Bill O’Reilly have agreed that Bill O’Reilly will not be returning to the Fox News Channel,” Fox's parent company said in a brief statement.

The abrupt dismissal ends O'Reilly's 21 years at the helm of The O'Reilly Factor, which started as The O'Reilly Report when the fledgling network began in 1996. He proved a steady ratings winner for the network over two decades and top ad generator, but also a lightning rod for controversy.

O'Reilly, 67, who recently signed a new multi-year contract worth more than $20 million a year, has been on vacation and was scheduled to return to the air Monday. "It is tremendously disheartening that we part ways due to completely unfounded claims. But that is the unfortunate reality many of us in the public eye must live with today," he said in a statement released Thursday afternoon.

"Over the past 20 years at Fox News, I have been extremely proud to launch and lead one of the most successful news programs in history, which has consistently informed and entertained millions of Americans and significantly contributed to building Fox into the dominant news network in television," he said.

In a message to employees, Rupert Murdoch and sons, James and Lachlan, who run 21st Century Fox, said the decision follows "an extensive review done in collaboration with outside counsel."

While confirming O'Reilly's ouster, the note was also full of praise for his success. "By ratings standards, Bill O’Reilly is one of the most accomplished TV personalities in the history of cable news," the Murdochs wrote. "In fact, his success by any measure is indisputable.

"Fox News has demonstrated again and again the strength of its talent bench. We have full confidence that the network will continue to be a powerhouse in cable news."

In a nod to the current Fox News staff, which has undergone extensive turmoil with the ouster last year of chairman and CEO Roger Ailes — and now O'Reilly — over allegations of sexual impropriety, the Murdochs said they wanted to "underscore our consistent commitment to fostering a work environment built on the values of trust and respect."

Before issuing his statement, the embattled newsman surfaced briefly in Rome, during his Italian vacation, where he shook hands with Pope Francis, who regularly ends his weekly audience by swinging by the VIP seats for a quick round of short greetings.

O'Reilly had steadfastly denied allegations of sexual impropriety and earlier this week his attorney, Marc Kasowitz said: "There is obviously an orchestrated campaign by activists and lawyers to destroy Mr. O’Reilly and enrich themselves through publicity-driven donations.”

O'Reilly will be replaced in the coveted 8 p.m. ET time slot by Tucker Carlson, whose current show is being moved up an hour. The 9 p.m. slot will go to The Five, relocating from its afternoon slot. The O'Reilly Factor will run through the end of the week with substitute hosts.