The entertainer and professional partner Kym Johnson are scheduled to perform a team tango alongside Kelly Osbourne and Louis van Amstel and Derek Hough and Joanna Krupa.
Speaking to Entertainment Tonight, he said: "I guess I'm going to announce, I'm going to be shirtless!
"I got to keep up with Louis and Derek, plus we're going to be taking our jackets off. I'm out there pumping the iron because I have to look good next to these guys and it's going to be a very physical number."
He added: "Let's put this into perspective. You have Derek Hough, one of the best dancers in the world, and me having to dance next to him with my jacket off. We're a quarter of a century apart, hello!"
Osmond also revealed that he is "so happy" to have reached the seventh week of the competition, but anticipates it becoming even more challenging as time goes on.
Dancing With The Stars airs tonight on ABC.