Her Majesty handed the baton to Paralympic sprinter Kadeena Cox in the palace forecourt to start the symbolic relay event. Some 7,500 bearers will carry the baton on a 90,000-mile journey to all 72 nations and territories of the Commonwealth over 294 days.
The journey ends in Birmingham, host city of the 2022 Games, next July.
At the ceremony, the Queen wore an orange Angela Kelly coat, with a flared wool print dress in shades of apple, olive and orange, and a matching orange hat. She also wore the large Nizam of Hyderabad diamond rose brooch.
She was joined by Prince Edward for the launch, along with Games mascot Perry.
Four-time Paralympic gold medallist Kadeena was given the honour of taking the baton on the first leg of its journey. She then handed it to Team England squash player Declan James and Olympic gold medal-winning Team Wales boxer Lauren Price, who took it down the Mall.
The televised event was another step in the Queen's gradual return to normality following the upheavals of the Covid outbreak.
But it will be April next year before regular events can take place inside Buckingham Palace again.
A £369million refurbishment programme has turned the state apartments the monarch uses for engagements into a building site.
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