Dame Shirley Bassey and Gary Barlow OBE will perform for the Queen to celebrate her 90th birthday.
It is not the first time Dame Shirley, 79, has sung before the monarch.
She has performed for her a the Royal Variety Performance and during The Queen's Diamond Jubilee Concert at Buckingham Palace in 2012.
The Queen's 90th Birthday celebration will be broadcast live on ITV on May 15.
Take That star Barlow, 45, was chosen to compose the Queen's official Diamond Jubilee single, Sing, with Andrew Lloyd Webber.
He performed the song with the Military Wives at The Queen's Diamond Jubilee Concert.
Barlow and Dame Shirley will join previously announced performers pop princess Kylie Minogue, tenor Andrea Bocelli, opera singer Katherine Jenkins and pop star Jess Glynne at the televised event, as the nation celebrates the milestone of its longest-lived monarch.
The celebration, taking place in the private grounds of Windsor Castle, will tell the story of the Queen's life from her birth in 1926, through the Second World War, to her coronation in 1953 and a reign spanning more than 60 years.