The Cornish attraction’s two enormous “biome” greenhouses hosted the show’s various experts, and crowds of local people brought their family heirlooms to be valued.
Camilla, who wore a green floral print dress by London-based designer Fiona Clare, brought along two of her own items to be valued – which will be revealed when the show airs at some point next year.
She took part in the “Guess the Mystery Object” game with jewellery expert Geoffrey Munn, and took a walk through the Eden Project’s famous gardens with the show’s presenter Fiona Bruce.
Bruce, who has presented Antiques Roadshow since 2008, hosted said the Duchess was a “good sport” who “had the full roadshow experience”.
“I think the duchess has really enjoyed visiting the Roadshow. She was such a good sport and talked to many of our visitors here, the crew and our specialists,” she said.
“She brought along a couple of items, and our book specialist and silver specialist talked her through them. So, I would say she had the full roadshow experience – this is the last programme we’re filming this year and what a wonderful way to end with such a special guest.”
Later, Camilla met with 16-year-old Dylan Kilpatrick and his mother Amanda Fishlock, from Cornwall, who had brought along a painting by their ancestor, 19th century artist Robert Ponsonby Staples, featuring a family on a seaside outing.
Ms Fishlock explained the artist was a relative on her mother’s side, which is how the painting came to be in their possession.
When asked what Camilla had thought of the painting, Dylan said: “She said she was jealous, she said she really liked the figure in the foreground.”
Camilla also spoke with Sandra Matthews, 77, who brought along a prayer book that she believes once belonged to the famous 19th century French actress Sarah de Bernhardt.
Ms Matthews said she had bought the book 30 years ago and found the actress’s name written on the fly leaf.
“Camilla was really interested because she knew who Sarah de Bernhardt was,” Ms Matthews said.
Elsewhere, Camilla met with former cabinet maker Christopher Thorp, who had a book of furniture prices printed by the London Cabinet Makers Union in 1811.
Mr Thorp, who has since retrained as a tropical ecologist working for Plymouth University, said the Duchess had asked him about his former trade and his interest in the history of the craft.