Simon Cowell turned his "Mr Nasty" image on its head and paid off the mortgage of a couple whose three-year-old daughter has cancer.
The multi-millionaire was touched by her story when he appeared on the US TV chat show Oprah and declared he would be her "guardian angel" from now on.
Host Oprah Winfrey showed Cowell a clip of Amy Stoen and her husband, Randy, from Claremont, Minnesota, who were struggling financially after their three-year-old daughter Madelaine was diagnosed with an aggressive form of cancer, alveolar rhabdomyosarcoma.
The couple take it in turns to travel more than 100 miles from their home each day so the girl, who has started losing her hair, can receive treatment.
Cowell greeted the Stoens on the Oprah stage yesterday and told them he had written a cheque for 162,000 dollars (£80,000) to pay off their mortgage.
"It doesn't stop there," he said.
"If there's any problem, I'm her guardian angel now."
The X Factor judge told Madelaine's parents: "I didn't know what to do in this situation other than to do something which I hope will help your situation.
"I know you are having problems with your mortgage. As of this afternoon, your mortgage has been paid off."
Mrs Stoen hugged Cowell and he added: "I never knew doing good could feel so good."
He said he had only just realised how good it was to give and told Oprah: "It's taken me 48 years. I credit you with this."
Cowell was on the show to launch X Factor winner Leona Lewis in the US.