The Take That star and X Factor judge travelled to Australia, Kenya, Jamaica and the Solomon Islands gathering 210 musicians for his song with Lord Andrew Lloyd Webber.
Copyright: BBC Dawbell
The images, taken from upcoming BBC documentary Gary Barlow: On Her Majesty's Service, show him interacting with local music-makers and approaching Princes Harry and Charles for their advice.
"We went on a journey with this record, meeting and recording with some beautifully talented singers and musicians," Barlow said.
"I can't believe we've managed to get the amount of people we got featured on this song, from all corners of the Commonwealth, but we did. I'm very proud of the result and hope people enjoy listening to it as much as we enjoyed making it."
'Sing', which also features Gareth Malone and The Military Wives Choir, will form part of a commemorative Jubilee album by Gary Barlow & The Commonwealth Band released on May 28. Some proceeds will raise funds for The Queen Elizabeth Diamond Jubilee Trust.
It has also been confirmed that the Military Wives and several of the Commonwealth musicians featured will perform the song at the Buckingham Palace Diamond Jubilee concert on June 4, which Barlow is curating.
Gary Barlow: On Her Majesty's Service will air on BBC One as part of the celebrations that same weekend.