The "X Factor" creator and judge was initially looking to get $20 million for the 12,000-square-foot mansion, but ended up putting the property on the market at $17.9 million instead.
The home was built for entertaining with five bedroom suites, a separate guest house, and a gorgeous swimming pool that lights up at night.
Zillow reports that Cowell is looking for a more family friendly home for himself, girlfriend Lauren Silverman, and their new baby.
Blair Chang at The Agency is handling the sale.