The CBBC presenter made a series of mistakes during his Viennese Waltz with partner Amy Dowden during Saturday night’s live show, which left him third from bottom of the leaderboard.
Judge Craig Revel Horwood called the dance “a terrible shame”.
“There were two rather large mistakes, sadly, which ended in entanglement,” he said. “The whole thing was over-egged.”
Speaking to host Claudia Winkleman afterwards, Karim said: “I’m just gutted I went wrong.”
Tearing up, he said: “Sorry, I don’t know why I’m getting upset. For me, going wrong is a no-no.”
As Amy then also got upset, she added: “I’m just so proud of him. It’s his birthday next week and more than anything, I want him to experience the magic of Blackpool and dancing there.”
Karim and Amy had to settle for sixth place on the night’s leaderboard, with their routine picking up 30 points.
It was a big fall for Karim, who was sitting pretty at the top last week when his Quickstep earned 39 points.
At the top of this week’s leaderboard was vlogger Saffron Barker and partner AJ Pritchard, whose Waltz picked up 39 points.
At the other end was BBC Breakfast presenter Mike Bushell and Katya Jones, with just 25 points for their Paso Doble.
The couples are all hoping to make it through to next week’s Blackpool special, but one pairing will find themselves eliminated during Sunday night’s results show, airing at 7.15pm on BBC One.