The wife of Scot Young, 48, a former fixer for the rich and famous, claimed in a court hearing Monday that Cowell concealed some of her estranged husband's cash.
Michelle Young claimed her husband, who was made bankrupt last year overan unpaid tax bill, was still worth more that $2 billion.
She argued in court that her husband was living with his mistress in London's exclusive Knightsbridge area, eating at the city's top restaurants, and driving a Ferrari.
When asked by her husband, who is acting on his own behalf in the court battle, "Who are hiding my assets?" she named Cowell, wealthy UK retailer Sir Philip Green and restaurateur Richard Caring.
When the judge asked her if she was really saying there was "a huge conspiracy involving a lot of people who would otherwise be regarded as respectable, to hide his assets?" she replied "Yes."
The judge said, "These are serious allegations against well-known people."
The jilted wife said her husband was a major shareholder in the hit TV show "American Idol" and that Cowell was assisting in hiding his assets.
Young is divorcing her husband citing unreasonable behavior and claimed he also had money in a series of offshore accounts.
Reps for Cowell and Sir Philip dismissed the allegations.