Fox News presenter Megyn Kelly, who has worked at the channel for 12 years, is leaving the network to join NBC, her publicist has confirmed.
Ms Kelly will host her own daytime news and discussion programme at NBC, as well as presenting an in-depth Sunday night news show.
The move deprives Fox News of its second most popular host after Bill O'Reilly.
Ms Kelly's contract with Fox was due to end later this year.
She was pushed into the international spotlight in 2015 when she accused Donald Trump of misogyny during a Republican presidential debate.
She later said that she would "not apologise for doing good journalism", following criticism from Mr Trump's supporters.
NBC News chairman Andrew Lack called Ms Kelly "an exceptional journalist" who has "demonstrated tremendous skill and poise".
"We're lucky to have her," he said.
Rupert Murdoch, executive chairman of 20th Century Fox, thanked her for 12 years of service.
"We hope she enjoys tremendous success in her career and wish her and her family all the best," he said.
Further details of Ms Kelly's news programmes will be unveiled by NBC in the coming months, the company said in a statement on Tuesday.
Ms Kelly, a lawyer-turned-journalist, joined Fox News' Washington bureau as a correspondent before being given her own prime-time show, the Kelly File.
The mother-of-three, from New York, began her career as a local news reporter in 2003, after nine years in law.
Kelly laments Trump's 'online nastiness'
During the US election campaign, Ms Kelly challenged now President-elect Donald Trump on his statements about women.
Her accusation of misogyny against the New York billionaire made her a target for his supporters and the subject of attacks from Mr Trump himself.
He accused the presenter of having "blood coming out of her wherever", later denying he was referring to menstruation.
In a move described by Fox News as "unprecedented", Mr Trump later refused to participate in shows hosted by Ms Kelly.