Sir Terry, 77, has fronted the charity event for 36 years, since its launch in 1980. It was announced he is unable to make the show tonight due to health reasons.
It is thought Terry will be having an operation on his back – meaning he is unable to present the six-hour show alongside Rochelle Humes, Tess Daly, Fearne Cotton and Nick Grimshaw.
In a statement he said: “Here we are on the 36th edition of Children In Need, every one of which I've been proud to present since it started in 1980, and for the first time, I won't be there, to cheer you on with word and gesture to another record-breaking year.
"I'm going to miss our wonderful, inspiring evening together, but I'll be with you, watching, cheering and donating to a magnificent cause."
While we’ll certainly miss Terry during this evening’s show, we can’t wait to have Dermot back on our screens.
Former X Factor host Dermot said: “I’d like to add my best wishes to Sir Terry for a speedy recovery, and I hope I do him justice and do my small part to make the night a success and make as much money as we can for disadvantaged children across the country.”
The BBC added: “We are incredibly grateful to Dermot for stepping in at such short notice but know he’ll do us and Sir Terry Proud.”
Children In Need is on tonight from 7.30pm on BBC One.