The former Atomic Kitten singer, who won the third edition of the reality show in 2004, said that Wright would regret his decision to quit The Only Way Is Essex for a spot in the jungle.
"Mark Wright has left The Only Way Is Essex - I can't believe it," she wrote in her OK column. "The only reason he's famous is because of that show and it's wrong that he thinks he's bigger than it.
"I think we'll see his true colours on I'm a Celebrity and I don't think he'll win it. The only girl he'll go for in there is Jessica-Jane Clement, but I don't know anything about her."
Amy Childs, who starred alongside Katona in Channel 5's first series of Celebrity Big Brother this autumn, said that she was confident of her former TOWIE co-star's chances in I'm a Celeb.
"I think he's going to shock all of us, definitely," she said. "He's brilliant, I've always been a big fan of Mark. I think Mark will win, definitely."
Wright and his I'm a Celebrity co-stars were joined by new campmates Sinitta and Pat Sharp last night (November 14).
The show continues tomorrow (November 17) at 8.30pm on ITV1.
> 'I'm a Celeb' Mark Wright, Freddie Starr eat turkey testes, pig anus
> Mark Wright: 'Right time to leave The Only Way Is Essex'