Fans must ask the street musicians, who will be performing Beyonce tracks, whether they have any tickets and make a donation for their performance.
The “Beyonce Buskers” could be found across the city throughout Friday.
A spokeswoman said: “Some people have donated as little as 10p, but others have given up to £10.”
Anyone who makes a donation is given three tickets to the concert tomorrow.
“We held these tickets back from the concert,” said the spokeswoman for Trident, which is sponsoring the event.
“The other 13,000 tickets were won by competition winners. It’s the first time tickets for a gig at the O2 have completely been given away.”
Beyonce, who is married to rapper Jay-Z, kicked off her UK tour in Liverpool on Wednesday.
She is also scheduled to perform in Manchester, Newcastle, Nottingham, Dublin and Belfast.
The 28-year-old singer was among the big winners at last week’s MTV Europe Awards in Berlin, picking up three awards including best female and best song – for Halo.
