Holly had been strongly rumoured to stand in for Ant, who is taking time out of the spotlight to focus on his recovery, after he was charged for drink-driving earlier this year.
Holly said: “I couldn’t be more excited to have been asked to stand alongside Dec for the next jungle adventure.
“I love Ant and want to send him my best wishes and support for a continued recovery. These are big shoes, not to fill, but just to keep warm for a little bit...
“Honestly, I’m a huge fan of ‘I’m A Celebrity’ and actually feel like I’ve won a competition to go and hang out on my favourite show!”
She added: “When is it a good time to tell Dec I’m scared of everything that moves?!”
Dec said: “I am hugely grateful to Holly for agreeing to accompany me to Australia this year. She was at the top of my list and I’m thrilled she said
Speaking about the absence of his best mate, he continued: “It will be a different kind of series but we will try our best to ensure it is no less fun and eventful for our loyal viewers.”
He added: “I am also pleased to hear Holly is scared of everything. I am almost stupidly excited at the thought of watching her during the eating trials!”
This year’s series of ‘I’m A Celeb’ will be the first time Ant and Dec won’t front the show together in the 16 years since it launched.
Ant confirmed the news he would not be hosting the series earlier this month, also pulling out of next year’s ‘Saturday Night Takeaway’.
He said at the time: “My recovery is going very well and for that to continue having spoken to Dec and ITV, I have made the decision to take the rest of the year off.
“I’d like to thank both Dec and ITV for their continued support and I look forward to getting back to work in the new year.”
Earlier this year, Holly revealed why she had chosen not to comment on Ant’s arrest on suspicion of drink driving.
The 37-year-old said she decided not to speak openly about the troubled star “out of respect for him”, adding that she felt it was something that nobody should be discussing.
She told The Guardian: “Everybody knows that Ant is a very good friend of mine and I’ve known him for a very long time.
“It’s not something anybody should be talking about. Out of respect for him, I love him to bits, it’s not something that I find very easy to talk about. Because it’s a friend. His is not my story to tell.”
She concluded: “He’s just got to look after himself, that’s all.”
Among the stars who have been rumoured for this year’s series include ‘Good Morning Britain’ host Kate Garraway former ‘Strictly Come Dancing’ professional Brendan Cole, ‘Coronation Street’ star Catherine Tyldesley, ‘Holby City’ actor Rosie Marcel and Made In Chelsea’s Jamie Laing.
‘I’m A Celebrity’ returns to ITV in November.