The O2 reopened on Friday after its roof was damaged in Storm Eunice a week ago.
The music venue, formerly the Millennium Dome, reopened at 10am on Friday morning.
Parts of the building’s roof was shredded on Friday, February 18, as the UK was battered by record-breaking wind gusts.
A number of concerts - including The Lumineers and rapper Dave - were postponed and have since been rescheduled.
UB40 will perform on Friday night.
Former UB40 member Ali Campbell has said he plans to “tear the roof off” the arena again as he returns to the stage in memory of his late bandmate Astro.
The singer said Astro, who died in November last year following a short illness, “would have wanted the show to go on” without him.
The 63 -year-old said: “I’m not the most talkative person on stage, I concentrate on singing, and Astro was always the mouthpiece. He would introduce the songs and, of course, I have got to do all that now.
“We are going to miss him terribly. I know he would have wanted the show to go on and that’s what we did.”
The O2 said a hole in the roof would remain visible for some time until it could be repaired.
The hole appeared above the venue’s shopping area, Icon Outlet, which will remain closed.
Steve Sayer, vice president and general manager of the O2, said: “Confirming our reopening after such a short closure is a huge testament to everyone who is working so hard to get us open again.
“Safety will always be our number one priority and as a venue, we have always been proud of the standards we hold and delivering a best in class fan and artist experience.”