Mel, who sits on the judging panel alongside Simon, Cheryl Fernandez-Versini and Louis Walsh, recalled the encounter on Alan Carr: Chatty Man while talking about her working relationship with the music mogul.
Speaking on the Channel 4 chat show, which will air tonight (7 November), former Spice Girl Mel, said: "I love him. I did actually walk in on him in a bath the other day. His dressing room is absolutely stunning."
A shocked Alan asked: "He's got a bath in the studio?"
Yes Alan, it turns out he does! Simon is the boss after all!
"He's got a bath. It's gorgeous," said Mel. "I was sitting there with my cup of tea on the sofa and he walked out of the bathroom with his towel on and went, 'Oh, hello darling, I've just had a bath'. And I went, 'Oh, can we talk about the show please?'"
Mel explained that Simon told her to sit down, and the pair talked in his dressing room, with Simon draped in just his towel!
Northern lass Mel was announced as the fourth and final X Factor judge in May, but she was also a guest judge on the show back in 2012.
Speaking about landing the job, Mel told Alan: "l I think my name's been in the running for a few years on the trot. I put myself on a flight [from Australia], went and knocked on Simon's door and said, 'Listen, we need to have a sit-down chat'.
"I had a room full of 20 executives," Mel continued. "I just went straight off the plane – probably looked like a dog's dinner – but I sat him down and said, 'Look, I want to do this show and these are the reasons why you need me on this show. Take it or leave it'.
"And then I got up and went, 'Got a plane to catch, bye'. And then they called me back. They made me wait 48 hours but it took me about that long to get back to Sydney anyway."
Alan Carr: Chatty Man airs tonight (Friday 7 November) at 10pm on Channel 4 with guests Mel B, Derren Brown, Sue Perkins, Nina Conti and music by Jungle.
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