The singalong came after a day of events to mark the first anniversary of the horrific event, including a service at Manchester Cathedral - including a one-minute silence observed across the United Kingdom - and a gathering in the city on Tuesday evening (22.05.18).
On May 22, 2017, at the conclusion of Grande's concert at the Manchester Arena, an explosion set off in the foyer by suicide bomber Salman Abedi, a British national of Libyan descent, killed 22 concertgoers and wounded at least 119.
The pop star told survivors and the families of victims that she was "thinking of you all today and every day".
"I love you with all of me and [I] am sending you all of the light and warmth I have to offer on this challenging day", she wrote in a tweet that included a bee, the civic symbol of Manchester.
As the Inquisitr reported last week, Ariana Grande recently opened up about the tragic events that occurred following her concert.
The 30-minute singalong in Albert Square featured...
In a message on social media, the American singer wrote: "Thinking of you all today and every day".
"The last thing I would ever want is for my fans to see something like that happen and think it won", she said.
His interactions have been captured by artist Ghislaine Howard, with her paintings on show in the city.
A memorial service, attended by Prime Minister Theresa May and Prince William, was also held in Manchester Cathedral.
The Lord Mayor of Manchester, Joan Hitchen, thanked the emergency responders who helped "bring our Manchester together again".
The victims were represented by 22 lit candles on the altar, which were made using wax from the thousands left in their memory by mourners in St Ann's Square at the time of the attack.
And at At 10.31pm, bells will ring 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.