The Take That singer has been working with the composer for a new song to celebrate The Queen's Diamond Jubilee year.
The track will be first heard on Chris Evans's BBC Radio 2 show at 8am tomorrow, Barlow confirmed.
He tweeted: "Our Jubilee song gets its first play tomorrow morning on @achrisevans 8am."
Barlow also revealed that the song's video will get its first play on the BBC Radio 2 website at the same time.
The X Factor judge has also been curating The Queen's Diamond Jubilee Concert, to be held on June 4.
Robbie Williams, Jessie J, Sir Paul McCartney, Stevie Wonder and Sir Elton John are among the long list of artists who will perform at Buckingham Palace.
He has also been travelling around the Commonwealth states as part of a documentary to coincide with the Diamond Jubilee celebrations.
Earlier today, Gary Barlow joined his Take That bandmates to receive the Ivor Novello 'PRS For Music Outstanding Contribution to British Music' award.
Watch Gary Barlow perform 'Back For Good' at the Children in Need Rocks Manchester event last year below: