Around 12,000 people will be at the concert in the Queen's gardens which will be televised for the country.
The gig is to be opened by Queen rocker Brian May playing God Save the Queen.
Then a beacon will be lit to start the chain of 1,600 other blazing beacons around the world, and hundreds of fireworks will be set off from the Palace roof.
And all over the UK people are celebrating with parades and street parties.
The parties will kick off at 1.00pm when church bells ring around the country.