Sarah, Duchess of York will co-host This Morning on Monday alongside presenters Alison Hammond and Dermot O’Leary.
Cat Deeley earlier this week stepped in to co-present three shows as ITV looks to replace former host Holly Willoughby, who announced her departure from the programme last month.
The duchess, 64, affectionately known as Fergie, has enjoyed previous visits to the This Morning studio and is guest editor, as well as co-host, of Monday’s show.
As part of her guest editor role, Sarah will oversee the live two-and-a-half hour programme, starting at 10am, which will delve into topics that sit close to her heart.
These include a look into the importance of defibrillators, the best way to rehome a dog and how to protect your skin.
There will also be an interview with Sir Cliff Richard, who recently released orchestral album Cliff With Strings – My Kinda Life, celebrating his 65th year in the music industry.
Sarah will co-host some of these items alongside Hammond, 48, and O’Leary, 50.
The duchess said: “I have appeared on This Morning before, but this time I am coming back in a very different role.
“I love live TV and am an enormous fan of the show, and the whole team is always lovely to deal with.
“I’m looking forward to being there for the whole morning, and thrilled to be guest editing the show which will mean getting to explore some topics that I’m passionate about.”
This Morning’s editor Martin Frizell added: “We are all delighted Sarah, Duchess of York wanted to come back here and I’m very happy for her to make some of my decisions on Monday.
“She has a great understanding of the show and how television works and I feel viewers will be really interested in the running order she is putting together.”
Sarah’s one-day stint as This Morning co-host and editor comes as presenter Josie Gibson enters the I’m A Celebrity… Get Me Out Of Here! jungle.
The ITV series returns Sunday evening with a line-up that includes former UK Independence Party (Ukip) leader Nigel Farage, food critic Grace Dent and Jamie Lynn Spears – sister to popstar Britney.
This Morning hit the headlines in May when Willoughby’s former co-host Phillip Schofield left the show after admitting to an “unwise but not illegal” relationship with a younger male colleague.
ITV said it was “not provided with, and did not find, any evidence of a relationship beyond hearsay and rumour” when it looked into the matter in 2020, and chief executive Dame Carolyn McCall said there will be an external review.
The daytime programme has faced increased scrutiny as employees past and present raised “claims of toxic working cultures, bullying, discrimination and harassment” with MPs.
Dame Carolyn told the Culture, Media and Sport Committee in August: “We are absolutely committed to enabling people to raise any issues or complaints they may have about working at ITV.”
The broadcaster updated its policy on work relationships in October.