The Hollywood star, who has also appeared in Sin City and Kill Bill, walked into the house on Thursday night (05Jan12), insisting his stay would be like a previous stint in rehab.
He quipped, "I don't know f**k all about Big Brother. But it's gonna be like rehab without the doctors."
Madsen was joined by Playboy twins Kristina and Karissa Shannon and British rapper Romeo Dunn.
U.K. soap stars Natalie Cassidy and Denise Welch were also among the star contestants, while retired, gay rugby star Gareth Thomas, who is to be portrayed on the big screen by Mickey Rourke, is also part of the new season's line-up.
The celebrities follow in the footsteps of Tara Reid, Stephen Baldwin and Pamela Bach, who have all previously taken part in the show.