The Mayor of London cut a ribbon just over 800ft above the capital to welcome visitors to the highest vantage point in western Europe.
He was joined on level 72 of London's tallest building by its architect, Renzo Piano, for the opening of the attraction, The View from The Shard.
Mr Piano said: "This building is magic for a number of reasons."First, because it's in London, second, because it's so tall, and third, because this building is a part of London. It's a sense of London."It's sad when London is sad, it's joyful when London is brilliant and joyful."
More top news
A man from London who was the subject of cruel online taunts has had the last laugh when a group of celebrities threw a party for him in LA.
Taffazul Hoque is 38 but suffers from autism and epilepsy. He is in danger of having a seizure and is sought urgently by his family.
Rachel Key told ITV London she was really nervous about presenting the trophy, but as a lifelong fan, supremely honoured.