The former member of the royal family also guest edited the ITV1 show and in the opening moments the programme’s chef Marcus Bean appeared to catch her eye.
As he previewed a pasta dish he was due to cook, Sarah told him “you’re very good looking”, then added “I meant the carbonara”.
Before the programme’s opening credits were broadcast, Sarah appeared behind the scenes and said: “I’m joining the family as co-host – fluff – alongside Alison and Dermot.
“And as guest editor for the day I’ve been working with the brilliant team behind the scenes to bring you some of the topics I’m most passionate about.”
Her first task was to go through stories in the newspapers with her co-hosts and guest Gyles Brandreth, and the discussion turned to I’m A Celebrity… Get Me Out Of Here!
The duchess was quizzed about whether she had been approached to appear in the programme, and replied “every single year”.
But when asked by O’Leary what Christmas dinners were like when the Queen hosted her family at Sandringham, she replied: “Beans on toast, Gyles over to you.”