The 41-year-old danced non-stop for a whole day and night and was cheered on by stars including Little Mix.
As his challenge came to an end, Dermot said: "Every ball in my body, in some shape or form, has had a hard time."
He quickly added: "On my feet!"
Discussing the challenge afterwards, he said: "[My feet] have seen better days. 2-6 last night was the worst. All my friends had left at 2am."
Celebrity chef Jamie Oliver also dropped in to lend his support. Sharing a photo with Dermot on Instagram, he wrote: "Now I'm dancing with Dermot for Comic Relief please text the number on his T shirt guys!!"
As well as his showbiz pals and the generous donators, Dermot also had support from his boss Simon Cowell. He tweeted: "Dermot good luck in your 24 hour dance challenge for Comic Relief. I've seen your dancing on X Factor, it'll be an endurance test for us all"
But, while we're used to seeing Dermot running around The X Factor stage, he did have some dance training from presenter friend and Strictly star Caroline Flack.
Speaking to the Mirror, Dermot explained: "I'm doing the Charleston with her and it's now my favourite dance."
Congratulations and a big well done to Dermot!