The 49-year-old said that she feels sorry for her fellow ex-cruise ship performer and would be "very proud" to sing alongside him.
Speaking on ITV1's Loose Women earlier today (November 25), McDonald said: "If Chris Maloney wants me to sing on the duet of X Factor with him, I will do it, I will do it with you.
"I would be very proud to sing alongside him. I think he's had a rough ride."
Admitting that she has been a fan of Maloney "right from the beginning", McDonald continued: "He's had a lot of criticism. I am proud of him standing up every week and doing as well as he's done.
"I am right on your side Chris, you keep on going, mate."
However, McDonald clarified that she wouldn't be prepared to get soaked like Rihanna when she performed 'Diamonds' on The X Factor this weekend.
"I don't want to get wet through," she stated. "I don't want to stand there with me dripping because my make-up would all run. "
Maloney's mentor Gary Barlow recently hit back at the treatment of the Liverpudlian singer, arguing: "He's a guy who's just singing on a talent competition, and it's like he's killed somebody. Give him a break."