Although the details of exactly what the song will be are yet to be announced, Simon has decided 100 per cent of the profit from sales will go towards Together For Short Lives.
The charity works with children's hospices and supports those who love and care for poorly kids who are unlikely to make it to adulthood.
Speaking about Together For Short Lives, Simon said: "I have worked with this charity for many years and I'm delighted that the X Factor winner's single sales will help families who are going through unthinkably difficult times.
"Together For Short Lives is such an inspiring and important charity which supports children all over the country. The money we hope to raise will really make a difference."
This weekend, Andrea Faustini, Lauren Platt, Fleur East and Ben Haenow will battle it out for a place in this year's final, which takes place on 13 and 14 December.
Despite finding himself in the bottom two on Sunday 23 November, Andrea is currently topping our readers' poll of who they think should win The X Factor 2014.
The last two remaining finalists will perform the winner's single on stage at Wembley Arena before this year's champ is announced.
This year's single will be the seventh charity release from The X Factor.