Journalist and TV presenter Piers Morgan left broadcaster ITV on Tuesday after long-running criticism of Prince Harry's wife Meghan, which reached a crescendo after the couple's interview with Oprah Winfrey.
During the Monday morning episode of Good Morning Britain, Morgan, 55, said "I'm sorry, I don't believe a word she says.
“I wouldn’t believe her if she read me a weather report.”
Morgan said she had sparked an “onslaught” against the royal family.
On Tuesday’s episode, he stormed off the set of the programme as weather presenter Alex Beresford was criticising his attitude towards Meghan. Morgan walked away, saying: “I’m done.”
He later returned to finish the programme.
"Following discussions with ITV, Morgan has decided now is the time to leave Good Morning Britain," ITV said on Tuesday evening.
"ITV has accepted this decision and has nothing further to add."
Britain's media regulator Ofcom also announced on Tuesday that it had launched an investigation into Monday's episode of the programme after receiving complaints about comments made about Ms Markle.
On Tuesday Ms Markle's father, Thomas Markle, appeared on the show on Tuesday to claim Prince Harry has not supported his daughter well enough since she joined the royal family.
"She pretty much ghosted all of her family on my side and her mother's side. She has nobody to reach out to," Mr Markle said.
"But the other thing is that I would think she could turn to her husband."
Co-host Susanna Reid said that Prince Harry had supported Meghan, to which Mr Markle replied: "Obviously not supported her that well."
He also said he had apologised "100 times" for co-operating with paparazzi photographers in the lead-up to the royal wedding.
He urged the couple to see him now that they only live about 110 kilometres away in southern California.
Mr Markle and his daughter have been estranged since her marriage to Prince Harry in 2018.
He pulled out of the wedding proceedings days beforehand after undergoing heart surgery.
During his television appearance, Mr Markle also said he did not think the British royal family were racist and hoped that an alleged remark from a family member about how dark the skin of Meghan's child would be was just a "dumb question".
But he believes the conversation should be investigated.
"I have great respect for the royals ... I don't think the British are racist.
"I think Los Angeles is racist, California is a racist, but I don't think the Brits are," Mr Markle said.
Meghan suggested that her son Archie, 1, had been denied the title of prince because there were concerns within the royal family about "about how dark his skin might be when he's born".
Mr Markle said: "I'm guessing and hoping it's just a dumb question from somebody, you know, it could just be that simple.
"It could be somebody asked a stupid question rather than being a total racist."
He said his daughter had let him down while he was ill.
"I was in a hospital bed the last time we talked and I never heard from them again," he said. "They didn't care if I died."
Mr Markle said Meghan and Harry "went way over the top" and should have waited, considering that Queen Elizabeth's husband Prince Philip, the Duke of Edinburgh, was in hospital.
"They should have waited considering the queen's age and Philip's age," he said.