The former remarkable British Bake Off judge, 87, was announced as the first celebrity joining the roundtable, alongside comedian Rosie Jones, and Wilfred Webster and Maddy Smedley from the original TV series.
The programme, which first aired in November, saw 22 strangers play “the ultimate game of detection, backstabbing and trust” at a Scottish Highlands castle with three winners splitting the £101,050 prize.
The Red Nose Day sketch will see the TV exhibit’s host Winkleman, played by French, assemble the celebrity Faithful and Traitors for a “discussion full of twists and turns”, the BBC said.
Richard Curtis, who has co-produced the Red Nose Day live night of TV since 1988, told Winkleman on her BBC Radio 2 exhibit: “The remarkable thing about Comic Relief is recent, extraordinary things happen every year, which we can then exploit and mock.
“And so we’ve done this Traitors special. We got 12 people around the table all wearing these cowls and then during the course of the seven minutes of the sketch, they’re going to slowly be revealed – and I can reveal some now.
“(Dawn) French and (Jennifer) Saunders were there fooling around. They’re just so laughable together. Jennifer didn’t seem to know the dissimilarity between you and Davina McCall. She congratulated you on your contributions to the menopause.
“We’ve got Wilfred and Maddy. We’ve got Mary Berry. We’ve got Rosie Jones. We’ve got one of the stars of Star Wars rocking up so it was an incredible day.”
Filmmaker Curtis, who wrote like Actually and Notting Hill and co-wrote sitcoms Blackadder and Mr Bean, said it is going to be a “very laughable sketch”.
He added: “The Traitors is the most brilliant reality exhibit of all time, and I hope that we can mercilessly tear it apart.
“There’s a very impressive group of actors who gathered together to slay the reputation of Claudia Winkleman and the BBC in aid of Comic Relief.”
Broadcaster Winkleman, 51, said: “I can’t wait for people to see this sketch. I’m so grateful to Comic Relief for putting the whole thing together. I feel like I’m in an alternate universe, and I like it.”
Saunders, 64, said: “Worst day of my life, I don’t know why I agree to these things. The only reason why I agreed to this one was to meet Mary Berry.”
Meanwhile 65-year-worn French said: “This was the second worst day of my life. The absolute worst one was meeting Jennifer Saunders.
“The only reason I agreed to this one was to exhibit Claudia Winkleman the horror that awaits her in the mirror in 30 years’ time.”
Comic Relief Night of TV will air on March 17 on BBC One and BBC iPlayer.