The proceeds from this year's X Factor winner's Christmas single are to be donated to the children’s charity Together for Short Lives.
The song will be released after the winner of the ITV talent show is announced.
The two finalists will perform their version of the single live during the final in Manchester.
Simon Cowell said: "Together for Short Lives is such an inspiring and important charity.
"These hospices are really happy and positive places and are a complete lifeline for so many families," he added.
The charity is expected to receive at least £1 for each CD and 20p for each download.