The actors won places in next weekend's final after impressing the public with a homage to Riverdance on the BBC One reality series.
Speaking after the result was announced, Maxwell admitted that she was "absolutely stunned" to be picked by voters.
She added: "I don't know what to say. Thank you everybody for voting for us and spending your money towards Comic Relief. That's brilliant, but blimey!"
The fate of sports stars Denise Lewis and Martin Offiah and This Morning host Fern Britton, who were runners-up in the viewer vote, then lay in the hands of the judges.
Panellists Dara O'Briain, Lisa Snowdon and Anton Du Beke eventually chose to save Lewis and Offiah, meaning that Britton was eliminated from the competition.
Lewis commented: "I can't believe it. I can't believe that we're through. Our dancers were all so fabulous - I'd like to say a big thank you to all the dancers, I think they made us look pretty good, thank you!"
The stars will now join Robert Webb, Dick and Dom, Paddy McGuinness, Keith Lemon and Jo Brand in next Saturday's final.