Following recent reports that viewers are growing increasingly unhappy with Cheryl, 31, Mel leapt to her defence.
Appearing on Alan Carr's Chatty Man, 39-year-old Mel said: "She is such a lovely girl, and man has she been through a lot, a lot – and it's all been on public display.
"She's just solid and true, and she's gorgeous, nice to talk to, she's not bitchy at all º trust me, if she was bitchy, she'd be on the floor. I'd 'ave her!"
When Alan then joked about an arm wrestling match between the pair, Mel joked: "That'd be quite hot, I'd like to do that.
"No, but she's really become a good friend of mine, I value her opinion outside of work, and we text each other, it's nice."
Mel, who also admitted to experimenting with women to spice up her sex life, revealed that she, Cheryl and Louis Walsh get 'naughty' on the X Factor panel.
She said: "I've got the gorgeous Cheryl next to me, and me and her, we talk about some naughty things on that panel, god knows what the sound guy thinks.
"And then I've got nutty Louis, who's just a bit lost sometimes but I love that about him. I do drawings of stuff that gets me into trouble a lot, and then I show it to Cheryl and she laughs, and then I show it to Louis and he goes 'wow, yeah!'"