The Opening Ceremony Celebration Concert features Duran Duran from England; Paolo Nutini from Scotland; the Stereophonics from Wales; and Snow Patrol representing Northern Ireland.
The 25-year-old Nutini took the stage first Friday, followed by Duran Duran, who formed in England's second-largest city of Birmingham in 1978.
The concert is pausing midway for the crowd to watch the opening ceremony live on several stadium-size screens, including the UK's biggest. Then the Stereophonics perform followed by Snow Patrol up to midnight.
Last year Hyde Park hosted a live TV party for the royal wedding of Prince William and Kate Middleton.