LONDON (VIP-NEWS) — A crowd of around 5,000 watched the rooftop show, which capped off a day of promotion for the Irish band's 12th studio album No Line On The Horizon.
U2 had been special guests on BBC Radio 1 and rumors of the gig appeared on internet message boards during the day.
The band performed four tracks during the 20-minute gig, including new songs Get On Your Boots and Magnificent.
They also performed Beautiful Day and Vertigo, as onlookers danced, clapped and sang along in the street below.
The BBC's Darryl Chamberlain, who was at the scene, said: "Some people tried to crowd on to traffic islands to see them… the crowd was screaming and cheering.
"Others were spilling out of pubs and shops to see it, and looking out of windows. It was a good natured crowd and people really seemed to be enjoying it."
Police closed Portland Place in Westminster to divert traffic away from the area.
The band all wrapped up against the cold, except The Edge who wore a short-sleeved lumberjack shirt and hat.
The performance was also broadcast live on DJ Chris Evans' BBC Radio 2 show.
U2's impromptu gig echoed The Beatles' 1969 rooftop performance at record label Apple's London headquarters.
Earlier the band revealed they are preparing to tour later this year, and hope to offer tickets with cheaper, recession-busting prices.
Frontman Bono told BBC Radio 1's Jo Whiley they had "something very special planned" for early summer.
He added that it was "a whole way of trying to do shows outdoors and make them very intimate".
In an interview on Radio 5 Live with Simon Mayo, Bono said that he had "gone off" Get On Your Boots a few weeks ago, but was now "back on it".
"It's a small song, a tiny little song, a little shot of adrenalin," he added.
Another song from the album, Breathe, had its live debut at an intimate Radio 1 concert on Friday morning.
Bono told the audience: "This is a great honor. This is the first time we've played these songs to people, so we hope we don't screw it up."
He said they were "trying" to work on some cheaper ticket prices, but added: "We're also going to have some very expensive ticket prices because rich people have feelings too!"
Radio 1 also apologized on-air immediately after Bono used an expletive to describe Coldplay's lead singer Chris Martin.
The BBC said it had received no complaints about it. According to BBC.co.uk.