Ant is currently focussing on his recovery following his arrest for drink driving earlier this year, and is taking an extended hiatus from all work commitments.
As a result, Holly is presenting the jungle-based reality show alongside Dec.
On Sunday, Ant tweeted: “All the very best of luck to the little fella and @hollywills for the show tonight. Lots of love from the big fella!!”
In another tweet, Ant, who turns 43 today, also thanked his TV partner for his birthday wishes.
Earlier in the day, Dec shared a snap of them dressed up as Homer and Marge from ‘The Simpsons’, which he captioned: “Happy birthday Homer, love Marge xx”.
The ‘This Morning’ host was first confirmed for the show back in August, saying at the time: “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...
“When is it a good time to tell Dec I’m scared of everything that moves?!”