Meanwhile, Queen Elizabeth II commanded attention in a shiny gold patterned dress, which she paired with low-heeled black shoes.
The event was a break from tradition as the Queen usually celebrates her actual birthday in private.
While Prince William and Kate Middleton are preparing for the birth of the third child, Prince Harry and Meghan Markle, whose nose wedding (before the wedding less than a month!), as representatives of the Royal family took all the responsibility for performing various official duties.
The summit was overshadowed by a row over Britain's treatment of Caribbean immigrants, while Charles himself also came under scrutiny.
The queen, Royal family members, The Prince of Wales, The Duchess of Cornwall, The Duke of York, The Duke of Cambridge, Prince Harry and Meghan Markle arrived at the ceremony for Elizabeth - the world's longest living reigning monarch.
But she was seen to be nodding along when Mr Balls, Frank Skinner and Harry Hill performed George Formby's signature song When I'm Cleaning Windows especially for the Queen.
At the end of the evening, Elizabeth went on stage to join some of the performers with her son, Charles.
She also celebrates an official birthday in June when soldiers parade through central London for the Trooping the Colour.
The major beneficiary of the event, televised live on BBC TV and radio, was the Queen's Commonwealth Trust youth charity, of which her grandson Prince Harry was appointed president this week.
Queen Elizabeth took the throne 66 years ago.
Last week, she attended the Commonwealth Heads of Government Meeting, which brought together the leaders of 53 countries, including former British colonies.