"The X Factor" judge and producer is expecting a baby with New York socialite Lauren Silverman, the estranged wife of his friend, real-estate mogul Andrew Silverman, the report said.
"She's around 10 weeks along," an insider told the magazine.
"Lauren and Andrew have been unhappy in their marriage for some time, and their divorce has been in the works for a while," a second source said. "As their marriage deteriorated, she and Simon became close."
Lauren is expected to move to Los Angeles so she and Cowell can raise the child together, the magazine said.