The German star - married to Kick-Ass director Matthew Vaughn - said it was one of the weirdest proposals she has received during her years in the public eye as one of the world's most in-demand beauties.
Schiffer discussed the megabucks offer - which she rejected - during an interview for the Jonathan Ross Show on ITV, to be screened on Saturday.
Asked about her oddest offers of work, she said: "Loads of weird ones but the strangest one was from an Arab prince. He asked if he could hire me for a dinner for a million pounds. I declined."
The 43-year-old also disclosed how she felt uncomfortable with the term "supermodel", which was used to describe the catwalk queens of her generation such as Cindy Crawford, Naomi Campbell and Elle Macpherson.
"When they started talking about 'super' and 'supermodel', I thought 'this is really insulting' - I want to be taken seriously in the high-end world of Chanel, Yves St Laurent, I don't want to be some supermodel'.
"So we all got a bit annoyed, which in retrospect was ridiculous. Supermodel sounds like a tabloid name, but then we realised 'hold on, maybe actually this is a good thing' because when we left fashion shows, suddenly there were thousands of people.
"I'm not exaggerating, and you had to have security people get you to your car - it just went crazy. I was on a photo shoot in Rome and people would see your name, you couldn't get out of the hotel. It was like (being) a rock star. I loved it."
Schiffer said she had been extremely shy during her early days of modelling and would flush with embarrassment, but it was hidden by layers of make-up.
"I thought it was never going to work until I put the make up on and you couldn't tell that I was turning red all the time."
:: The Jonathan Ross Show is screened at 9.20pm on Saturday.