The hitmaker revealed how the late 15-year-old’s mum Charlotte inspired her to change the set list for the event in an emotional speech at the Emirates Old Trafford.
Describing the moment, the 23-year-old said she had to change the running order after being convinced Olivia would have wanted her to sing her biggest hits.
Fighting back the tears, Ariana said: ”I want to thank you so much for coming together and being so loving and strong and unified. I love you guys so much and I think the kind of life and unity you're displaying is the medicine the world needs right now.”
The US star continued: ”I had the pleasure of meeting Olivia's mummy a few days ago and as soon as I met her I started crying and gave her a big hug. She told me to stop crying as Olivia wouldn't want me to cry and then she told me Olivia would have wanted to hear the hits.
BBC • ITV
Ariana Grande changed the setlist for Olivia Campbell
Ariana Grande revealed she changed her setlist for victim Olivia Campbell One Love Manchester concert Mon, June 5, 2017
One Love Manchester: Ariana Grande puts on an epic show with famous faces including, Miley Cyrus, Katy Perry, Coldplay and Liam Gallagher.
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Ariana Grande performs on stage during the One Love Manchester Benefit Concert
“So, that being said, we had a totally different show planned and we had a rehearsal yesterday but changed everything. Tonight has been filled with love and fun and bright energy, so thank you for that."
Ariana then launched into an energetic performance of her single Side to Side, in honour of the 22 victims who were killed on May 22.
Those watching at home were particularly taken aback by the heartfelt speech and one person wrote on Twitter: “Many emotional moments tonight but the most touching was Ariana's speech for Olivia Campbell and her mom. Strong & brave. #OneLoveManchester.”
Another wrote: “Lovely words from @ArianaGrande for Olivia Campbell, one of the victims. Respect for her mom who lost her beautiful girl #OneLoveManchester.”
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“Rest in peace Olivia Campbell. Forever in our hearts. This one's for you! #OneLoveManchester,” added a third viewer.
One Love Manchester was held to raise money
Ariana Grande held a benefit concert in aid of those killed and injured in the Manchester attack
The petite star was joined by a host of musicians for the benefit concert to honour those who lost their lives in the bombing that occurred at the end of her sold-out gig last month.
One star who joined the American singer was Justin Bieber who gave an emotional performance of Love Yourself.
One Love Manchester concert is now available on BBC IPlayer.