The star had previously been flanked by a bevy of A-list superstars as she sang One Last Time for the concertgoers, with Katy Perry, Miley Cyrus, Niall Horan, Little Mix and more behind her.
The song has since hit No1 on iTunes.
Grande then ran back onto the stage to sing the classic ditty, which left concertgoers in tears.
The 23-year-old herself also had to hold back tears as she sang.
She had earlier said: “From the bottom of my heart, I want to thank you all for being here today.
“I want to thank you all for coming back together and being strong and unified.
“I love you so much, and I think the love and unity you are displaying is the medicine the world needs right now.
“And I wanna thank you for coming tonight. I love you so much.”