Simon Cowell has been left traumatised after his house was burgled in the early hours while his family was inside.
The crooks stole cash and jewellery in the 2am raid on Friday (December 4).
Cowell, girlfriend Lauren Silverman and son Eric were at the £35million mansion when the burglars struck.
A source said: "It was clearly a very traumatic incident. Simon is just relieved that his family was safe and all right Their safety is his number one priority."
Police rushed to the luxury house in Holland Park, Kensington, but the burglars had fled.
It is understood Cowell, 56, and his family were asleep at the time of the break-in and that a security guard called the police.
Scotland Yard said: "No arrests have been made but inquiries are ongoing."
It is not the first time the X Factor judge's home has been targeted. In March 2012, stalker Leanne Zaloumis broke in wielding a brick and hid on a shelf inside his giant wardrobe.
Cowell was watching TV when he heard a loud bang coming from his bathroom.
Armed officers found the intruder smashing his window with the brick, her hands covered in blood.
Zaloumis was later given a 12-month community order. She spent 102 days in custody until her release with an electronic tag.