The TV star, 24, later apologised for being asleep when The Zoe Ball Breakfast Show tried to get hold of him at his planned slot, just after 7am.
When they did eventually get through, the Emmy-nominated actor told Ball: “I’m so embarrassed.
“I haven’t missed a single interview for however long… I’m so, so sorry.
— Zoe Ball (@ZoeTheBall) July 31, 2020
He said being nominated for an Emmy this week, for TV series Normal People, had “been a little bit nuts”.
“It probably is the reason that I’m up a little bit late.
“I’ve slept through my alarm a little bit,” the Irish star said.
Ball quipped: “You are totally forgiven!”
Mescal, who appeared on Thursday night at a livestreamed gig from the British Natural History Museum, responded: “I’m not forgiving myself… I’m so angry with myself!”
The actor’s co-star Daisy Edgar-Jones, who earned critical acclaim for her role in Normal People, missed out on an Emmy nod.
“Getting to work with Daisy on a daily basis is totally and utterly the highlight of my career, to date, and I imagine that’ll be the case for a long long time,” Mescal told the BBC Radio 2 show.
“I totally share what happened to me this week with her because she is just an extraordinary human being and an extraordinary talent.”