The Countdown star is one of several former campers who have headed back into the jungle for the special series of the show, this time in South Africa instead of Australia.
The contestants had been under wraps for months but at the weekend hosts Ant and Dec spilled the beans on Saturday Night Takeaway, revealing that celebs including Vorderman, actor Helen Flanagan and supermodel Janice Dickinson were among the line-up.
Speaking on ITV’s Lorraine, Vorderman revealed it was a challenging experience.
“We filmed it all last autumn, like people do Great British Bake Off or The Apprentice or whatever," she told host Lorraine Kelly.
“And then obviously I didn’t know who else was going to go in but every one of the people who go in had been on it before so there are a number of Kings and Queens of the Jungle who are also in it.
“There are a lot of head to head trials and things like that.
“But it is brutal.”
When Kelly asked if it was harder than when she first did I’m A Celebrity in 2016, Vorderman groaned and said: “Oh, like, another level. Another level.”
Ant and Dec have previously teased that there will be differences between the All-Star version and the usual series, with campers competing to become the first ever I'm A Celebrity Legend of the Savannah."
Speaking earlier this year, Ant said: “It's good, and it's slightly different to the show we do in Australia because they go head to head in trials and whoever loses leaves, so it's quite brutal.”
The other campers who have been revealed so far also include cricket star Phil Tufnell, Olympian Fatima Whitbread, boxer Amir Khan , Diversity’s Jordan Banjo, former royal butler Paul Burrell and Happy Mondays star Shaun Ryder.
Watch: Carol Vorderman denies going to the races with Matt Hancock