Megyn Kelly's return last week to Fox News as a guest on "Tucker Carlson Tucker CarlsonJudge tosses Karen McDougal's defamation suit against Tucker Carlson OVERNIGHT ENERGY: House passes sweeping clean energy bill | Pebble Mine CEO resigns over secretly recorded comments about government officials | Corporations roll out climate goals amid growing pressure to deliver Former Florida attorney general calls Kyle Rittenhouse 'a little boy out there trying to protect his community' MORE Tonight" delivered more than 4 million viewers, helping the program be the most-watched on cable, according to Nielsen Media Research.

The Kelly interview, which included pointed commentary about her former employer, NBC News, marked her first TV appearance in almost one year and her first appearance on Fox News in nearly three years.

Kelly made a highly visible jump from Fox News to NBC News in 2017, signing a three-year contract with the Comcast-owned network and gaining her own morning show.

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The onetime attorney parted ways with NBC nearly one year ago after controversy over her comments during a Halloween costume panel stating that wearing blackface was "OK" when she was growing up "as long as you dressed up as a character."

She quickly apologized for the comments, but her show was still canceled.

Kelly also drew ire of NBC executives when she showed a willingness to book sexual misconduct accusers of former "Today" host Matt Lauer Matthew (Matt) Todd LauerComcast shareholders reject proposals for outside sexual harassment investigation at NBC Ronan Farrow fires back at Matt Lauer 'shoddy journalism' accusation: 'Just wrong' Megyn Kelly calls independent Tara Reade interview the 'wave of the future' MORE, with some media experts suggesting it helped lead to her exit from the network.

During the Fox News appearance, Kelly called on NBC News to bring in an outside firm to investigate sexual misconduct allegations against Lauer.

"There needs to be an outside investigation into this company,” Kelly told Carlson on Wednesday night. "They investigated themselves. That doesn’t work. This is how it's done. You get somebody on the outside who can be trusted," she added.

Linda Vester, also a former NBC News host, also said in an interview with Fox News's Shannon Bream Shannon BreamFox Business host Lou Dobbs in self-quarantine after staffer tests positive for coronavirus Fox Business to temporarily cease production of two daytime programs amid coronavirus precautions Fox News pulling overnight repeats, to air live 24-hour coverage of coronavirus pandemic MORE that she thought an external investigation needed to be opened.

Fox News allowed an outside firm to investigate sexual harassment allegations against then-chairman and CEO Roger Ailes in 2016, which led to his exit just three weeks after the investigation was launched in July of that year.

NBC confirmed through a spokesperson to The Hollywood Reporter on Thursday that it will not open a new investigation.

"There is no additional investigation being launched. We are very confident in the report that was conducted," spokeswoman Hilary Smith told THR.

"We fired Matt Lauer within 24 hours of learning what he did, and promptly launched a corporate investigation," she added. "Based on our investigative findings, we have swiftly taken appropriate actions to address the situation and improve workplace culture. It is also worth noting that this was a corporate investigation that was conducted by an almost entirely female team, none of whom are part of the News division."

Overall, Carlson drew 4.06 million total viewers to win the cable news race with Kelly's appearance, followed by Sean Hannity Sean Patrick HannityFormer Florida attorney general calls Kyle Rittenhouse 'a little boy out there trying to protect his community' Sunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Cruz: Trump should nominate a Supreme Court justice next week MORE with 3.65 million viewers. MSNBC's Rachel Maddow Rachel Anne MaddowGOP lawmakers distance themselves from Trump comments on transfer of power Schiff urges Trump administration members to resign: 'You cannot maintain your silence' Michael Cohen: Trump hates Obama because he's everything he 'wants to be' MORE was third with 3.44 million.

In the 25-54 demographic that advertisers covet most, Carlson registered 689,000 viewers, followed by Hannity's 632,000 and Maddow's 574,000 in the category.