The Take That leader has been working with producer Labrinth - who was behind Tinie Tempah's hit 'Pass Out' - and an all star cast of young UK talent on the track, which is the first non-comedy single the charity has ever released.
Gary told The Sun newspaper: "I think this is a brilliant project. Children In Need has a history of doing upbeat singles with comedians but it's a serious charity doing a lot of hard work for serious causes.
"It's time to do something with artists who young people actually listen to. I've done these things before, I'm used to doing group situations, I like it - it's a challenge. It hasn't been easy. But bless him, Labrinth and his manager have been the key to the whole thing.
"I met up with them and they started doing the whole lot, talking to friends etc, and all of a sudden the word started to get out. Hopefully we should be nailed on for a No1 - and raise loads of money in the process."
The single is out on November 13, but a name has yet to be given to the collective which will release it.