The crowds ended a day of remembrance by joining in with the hits of Oasis, Take That and Ariana Grande, the singer whose young fans were the target when Salman Abedi detonated a suicide bomb at Manchester Arena. The pop star wrote in a tweet to survivors and the families of victims that she was "thinking of you all today and every day". "Thinking of you all today and every day", she wrote, with an emoji of the bumblebee which is a symbol of Manchester.
One of the groups performing is the Manchester Survivors Choir, a group made up of those who were there on the night of the attack, and a local school choir that performed onstage with Grande at the One Love concert.
Thousands of people came together in Manchester last night for a mass singalong in memory of the 22 victims of last year's terrorist attack. The Lord Mayor of Manchester, June Hitchen, and the Bishop of Manchester, the Right Reverend David Walker, were also part of the event.
Twenty-two concertgoers were killed, and police say more than 800 people were left "with physical and deep psychological injuries".
Manchester Together in Albert Square featured songs by Elbow and Oasis.
"That's why I did my best to react the way I did", Grande said.
Also in attendance at the service were the grandparents of 15-year-old Olivia Campbell-Hardy who was killed in the attack.
To cheers, Manchester United great Ryan Giggs said: 'Manchester is a city of music and is a city of love, and we are sending out love and prayers on this emotional day'.
The service was attended by families of the bereaved as well as British Prime Minister Theresa May, Labour Party leader Jeremy Corbyn, Nicola Sturgeon, First Minister of Scotland, and Prince William, who read out a passage from the Bible and later met some of the families of the victims.
"We were very lucky, we know how lucky we are", he told Sky News.
Nine-year-old Molly said she was taking part because it was "a good thing to do for all the people who can't be here", while Matty, 14, said the unity in singing "is what Manchester's all about".
And thousands of members of the public have written messages of support on cardboard tags, attaching them to 28 "Trees of Hope" that form a trail from St Ann's Square to Victoria Station.
At 10.31pm, bells rang out from the city's Town Hall, St Ann's Church and St Mary's RC Church to mark the moment when the attack took place 12 months ago.