Robbie Williams and Alexandra Burke are among the stars set to perform at a benefit concert for servicemen and women at Twickenham Stadium.
The concert, which takes place on 12 September and will be shown on BBC One, will also feature comic talent including Bruce Forsyth and Jack Dee.
Some 60,000 fans and troops are expected to attend the event.
Proceeds will go to the Help For Heroes charity, which raises funds for wounded service personnel and their families.
Other musical acts already confirmed for the line-up include rapper Plan B, The Saturdays and James Blunt.
TV comics Michael McIntyre and Jason Manford are also taking part in the gig.
Williams, who recently announced his return to Take That, said he was "honoured" to be asked to take part, and paid tribute to UK service personnel engaged in Afghanistan.
"Their dedication to our country is phenomenal and we are all so proud of them," he said.
Bryn Parry, head of the Help For Heroes charity, said: "Our boys and girls, both those operating in the remote patrol bases and those recovering from life changing injuries, will hear this concert and know that they are in the forefront of our minds.
"They are not forgotten, wherever they are."
Some 150 personnel injured in combat will attend the show free of charge.
Tickets for the concert are due to go on general sale at 0900 BST on Wednesday 4 August.