The track is 'One Vision', a new version of the Queen classic.
The pair will debut the anthem on May 11 at London's Royal Albert Hall, with the Duke and Duchess of Cambridge and a host British Olympians present, BBC News reports.
The song's lyrics have been slightly adapted for their new purpose, with the phrase "one man" being changed to "one team" throughout the song.
Freddie Mercury's decision to sing "fried chicken" instead of "one vision" during the fade-out has also not been followed.
Walsh, who previously revealed that she would be involved in the official song, said: "So excited to be supporting Team GB with Alfie. Bring on the gold medals!"
Boe commented: "It's a huge honour to sing 'One Vision' for Team GB with Kimberley. Being a massive Queen fan, I was very excited about recording the track - I hope everyone likes it."
Watch a behind-the-scenes video of Walsh and Boe recording 'One Vision' below: