On stage Sunday, Braun paid tribute to the fans who turned out just hours after Saturday's London attack.
The song had been played at some of the funerals of the people who lost their lives during the attack.
Sunday's three-hour event, broadcast and live-streamed for an audience of millions on television and the Internet, was a moving expression of resilience - by both the performers and the crowd in Manchester, members of which could be seen enjoying themselves in lovely reaction shots filled with wide grins, hoisted drinks and children seated on their parents' shoulders.
"Before we go any further, I want to thank you all from the bottom of my heart for being here today".
Grande and her team organized the event to honor the 22 victims who were killed by a suicide bomber outside of Manchester Arena after her "Dangerous Woman" tour let out on May 22. "As unfortunately, we saw yesterday, evil will test us, it will show its face again".
During the show Grande duetted with Miley Cyrus on Crowded House's Don't Dream It's Over and was joined on stage by her boyfriend Mac Miller as they performed their collaboration The Way and Miller's track Dang!
British singer Marcus Mumford held a moment of silence before performing at the Manchester benefit concert Sunday.
More than 14,000 tickets for the concert were set aside to be given free to fans who attended the original show.
Her story inspired the singer to push forward with the show when she didn't have the strength to do so, because of Olivia's mother told her she would have loved the idea of the concert and would have loved to hear all of Ari's hit singles.
She later came back to the stage for a moving performance of Somewhere Over The Rainbow, which saw her burst into tears mid-song.
Despite the atrocities, fans including those injured in the Manchester Arena on May 22, headed to the venue in their droves, proudly wearing clothes emblazoned with the slogan, "We stand together".
He said: "I'm proud to say that there's a TV set up in all hospitals and all those kids are watching us now".
"Finally, our thoughts remain with all those affected by the heartbreaking events of Monday May 22". "We need to show that we are not scared", he said, before joining his family in a frenzied round of selfie-taking.