Showbiz
The music mogul nabbed 21% of the vote to beat competition from actress Joanna Lumley (20%) and newsreader Trevor McDonald (17%) in the poll of more than 100,000 people by MSN Entertainment.
Lumley, who recently met PM Gordon Brown to discuss Gurkha rights, has previously denied claims that she will run for political office.
"I am too old to learn the rules, to talk their talk or walk their walk," she told the Daily Mail. "I certainly don't have the stamina anymore."
Other celebrity candidates to run the country included Radio 1 DJ Chris Moyles (9%), X Factor judge Cheryl Cole (8%) and comedian-turned-actor Russell Brand (8%).
The top ten celebrity favourites for Prime Minister are:
1. Simon Cowell
2. Joanna Lumley
3. Trevor McDonald
4. Chris Moyles
5. Cheryl Cole
6. Russell Brand
7. Katie Price
8. Fern Britton
9. Will Young
10. Delia Smith
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