Cowell is reportedly so keen to get the superstar on board the struggling show he will offer her the choice of a judging role on either of its UK or US versions.
The 51-year-old believes the "Umbrella" singer's worldwide appeal and genuine star quality will provide a huge ratings boost to whichever show she chooses.
"Simon is a huge admirer of Rihanna and knows she's star quality. As well as bringing an aura to the panel thanks to her current standing in music, she is also feisty and will make great TV. Simon loves these sort of characters," a source said.
The latest series of 'The X Factor' has flopped, with last weekend's final pulling its lowest audience for seven years.
The show's fortunes have waned since Cowell left the judging panel in 2010 to concentrate on the American version of the show. But ratings have also been disappointing after two series there.
Cowell, 53, also wants Rihanna's on-off boyfriend Chris Brown to take over from departing judge LA Reid on the American show.