ITV's exclusive broadcast of the explosive Harry and Meghan interview was watched by 11.1 million people on Monday night.
Viewing figures peaked at 12.3 million for the channel as the couple shared their story of why they left the UK and stepped back from the Royal family.
It was the channel's biggest peak audience since the 2019 Rugby World Cup Final.
The sit down with US chat show host Oprah Winfrey was first on American channel CBS overnight on Sunday reaching an estimated 17.1 million US viewers.
Buckingham Palace is yet to respond to any of the claims made in the interview, including the allegation that a member of the family - not the Queen or the Duke of Edinburgh - raised concerns about their unborn son's potential skin colour.
Meghan says concerns were raised about the colour of their unborn child's skin
In the deeply personal conversation with the couple's friend, Meghan said she had experienced suicidal thoughts during her time in the Royal Family, revealing she got to the stage where she "just didn’t want to be alive anymore."
ITV's Good Morning Britain host Piers Morgan delivered a scathing review of the interview, saying he did not believe Meghan, prompting mental health charity Mind to issue a statement about the presenter.
The charity, which has partnered with ITV for their 'Get Britain Talking' mental health campaign, said it is "in conversations" with the channel over Mr Morgan's comments.
ITV chief executive Carolyn McCall said leadership was "discussing" the matter.
Piers Morgan storms off GMB after his behaviour is branded 'diaboloical'
Support poured in for the couple from celebrities on either side of the Atlantic.
Rugby player Gareth Thomas described Harry as "an amazing human being," while Little Mix member Leigh-Anne Pinnock said the interview showed the "underlying racism lying within the royal establishment".
In the US tennis star Serena Williams described Meghan as her "selfless friend" who "teaches me every day what it means to be truly noble".
Charles ‘stopped taking Harry's calls’
Meghan’s battle with loneliness
Meghan said she was ‘silenced’ and accused royal family of failing to protect her
Worries that denying Archie a title could leave him without protection
Kate ‘made Meghan cry’ before her wedding
Quizzed on the interview at Monday's Covid briefing, Prime Minister Boris Johnson refused to respond to the couple's claims or comments but said he had "the highest admiration" for the Queen.
Labour leader Keir Starmer said the couple's allegations should be taken seriously.
Oprah With Meghan and Harry is available to watch on demand on ITV Hub for viewers in the UK.