The 63-year-old veteran host will front the upcoming 19th season of The Ellen DeGeneres Show before ending the series in 2022.
DeGeneres, whose reputation has copped a beating in the past 12 months due to toxic workplace allegations, hosted its very first episode back in 2003 and has since led more than 3000 shows.
She said her reasoning for quitting was because it was "just not a challenge anymore".
"When you're a creative person, you constantly need to be challenged. And as great as this show is, and as fun as it is, it's just not a challenge anymore," DeGeneres told The Hollywood Reporter.
The website reports DeGeneres informed her staff on May 11 and will sit down with talk show queen Oprah Winfrey to discuss the news on tomorrow's episode of the Ellen show.
"Although all good things must come to an end, you still have hope that truly great things never will," Warner Bros.' unscripted TV president Mike Darnell told the publication. He added it was "an absolute phenomenon," and the "premier destination for both superstars and incredible heartfelt human-interest stories."
It comes after a report emerged in August that DeGeneres was on the verge of walking away from her show amid the PR crisis.
"She feels she can't go on and the only way to recover her personal brand from this is to shut down the show," a source told the Daily Mail.
"The truth is she knew what was going on, it's her show. The buck stops with her. She can blame every executive under the sun – but Ellen is ultimately the one to blame."
DeGeneres' reputation went from bad to worse last year when a March tweet claiming she was "notoriously one of the meanest people alive" went viral for all the wrong reasons.
There were more than 1000 replies to the initial tweet, with people detailing their not-so-nice experiences with her.
The aftermath was even more brutal, with countless staff coming forward on the record with their own stories of bullying.
Ellen DeGeneres hosted the very first episode back in 2003 and has since led more than 3000 shows. Photo / AP
A Warner Bros internal investigation following months of negative press led to the firings of top producers Ed Glavin, Kevin Leman and Jonathan Norman mid last year.
Addressing toxic workplace claims for the first time after her return to TV for season 18 in September, DeGeneres admitted she was a "work in progress" but pleaded to viewers that she is still "the person you see on TV".
"As you may have heard this summer there were allegations of a toxic work environment at our show and then there was an investigation. I learned that things happened here that never should've happened," she said.
"I take that very seriously, and I want to say I'm so sorry to the people who were affected.
She admitted being known as the "be kind" lady is "a tricky position to be in".
"Sometimes I get sad. I get mad. I get anxious. I get frustrated. I get impatient. And I am working on all of that. I am a work in progress.
"And I am especially working on the impatience thing because … and it's not going well because it's not happening fast enough."
A controversial friendship
Following decades of being a popular figure, DeGeneres' woes slowly began in 2019 when an image of former US president George Bush and DeGeneres sitting side-by-side and laughing at an NFL game sparked fierce debate online after being labelled "irresponsible and dangerous".
Many criticised DeGeneres – a prominent gay, liberal and outspoken LGBTQI activist – for cosying up with the former Republican president, who once endorsed a constitutional amendment against same-sex marriage.
Bush also entered the US into a war with Iraq and Afghanistan under the later-disproved belief that they possessed weapons of mass destruction.
Among the most vocal critics – actor Mark Ruffalo:
Sorry, until George W. Bush is brought to justice for the crimes of the Iraq War, (including American-lead torture, Iraqi deaths & displacement, and the deep scars—emotional & otherwise—inflicted on our military that served his folly), we can’t even begin to talk about kindness. https://t.co/dpMwfck6su
American actress Dakota Johnson, of Fifty Shades Of Grey fame, visited DeGeneres for a chat in December 2019.
Things got off to a frosty start when DeGeneres mentioned Johnson's recent 30th birthday.
"Happy belated birthday," DeGeneres said. "How was the party? I wasn't invited."
As the audience laughed, Johnson replied sternly, "Actually, no, that's not the truth, Ellen. You were invited."
Johnson told DeGeneres she made sure to invite her to her party this year because she gave her "a bunch of s***" last year when she didn't receive an invite to her party.
"I did invite you and you didn't come," Johnson repeated.
DeGeneres was sceptical at first: "This time you invited me? Are you sure? I don't think so."
"Ask everybody," Johnson said. "Ask Jonathan, your producer."
Further deepening the rift: It later emerged that Ellen had skipped the party because it was the same weekend she was with Bush at the NFL game.
Viral Twitter thread
In March, writer and comedian Kevin T. Porter tweeted: "Right now we all need a little kindness. You know, like Ellen DeGeneres always talks about!
"She's also notoriously one of the meanest people alive. Respond to this with the most insane stories you've heard about Ellen being mean & I'll match every one w/ $2 to @LAFoodBank."
It's safe to say Porter could not have predicted the onslaught that would follow.
Ellen DeGeneres' reputation has copped a beating in the past 12 months due to toxic workplace allegations.
TV writer Benjamin Siemon replied to Porter's tweet with: "She has a 'sensitive nose' so everyone must chew gum from a bowl outside her office before talking to her and if she thinks you smell that day you have to go home and shower."
Author Allison Freer wrote: "Was working on a show @ WB that was next to her stage. Was our showrunner's 50th Bday. Caterer grilling steaks outside for special fancy lunch. Ellen sent someone over to demand they stop, as she doesn't eat meat. She's the worst."
Employee allegations
On July 17, Buzzfeed published a bombshell report last year in which a group of former and current Ellen Show staff sensationally spoke out against the program, making shocking allegations about the environment behind the scenes of the hit daytime show.
Ten former and one current DeGeneres employee – all speaking anonymously – described a "toxic work environment" with a culture of "racism, fear and intimidation".
"That 'be kind' bulls**t only happens when the cameras are on. It's all for show," one former employee is quoted as saying.
Former employees alleged to Buzzfeed that they'd been fired for taking medical leave, attending family funerals, and one for posting a selfie in the office on her Instagram Stories.
One person who escaped relatively lightly in the article: DeGeneres herself. She barely figured in the employee complaints, aside from one employee alleging they were told never to talk to her if they saw her around the office.
