The 24-year-old singer looked stunning in a simple ensemble as she went braless in a white t-shirt, tiny denim shorts and thigh-high boots for the star-studded event.
And in a heartfelt speech, the US singer praised Ariana Grande for holding the benefit gig to raise money for the victims of the Manchester bombing that occurred at the end of her concert on May 22.
With tears in her eyes, she told the audience at the Emirates Old Trafford: “I’m so honoured to be at this incredible event, surrounded by all you incredible people. The most important responsibility we have on this planet is to take care of one another and look what we’re doing today and how amazing that is.
The Hannah Montana star then went on to discuss how Ariana has always helped her with her own charity The Happy Hippie, she continued: “We started raising awareness by putting together something like this, a bunch of artists of all different types, but was held in my own backyard. So right now I feel like I’m at home in Manchester, so I thank you for that.
“I started the Happy Hippie because I wanted to encourage other people to fight for what is right, and that is how me and Ariana became close as she was the first artist to say yes to be a part of the movement.
“As humans we should always be who we say we are, and Ariana has proved that. She says she is a good role model for some of you girls right now and I think she has proved that by putting this together and allowing all of us to be a part of it.”
The daughter of Billy Ray Cyrus then went on to perform her song Inspired for all those affected by the attacks.
Miley later joined Ariana, 23, as they teamed up to cover Crowded House’s hit song Don’t Dream It’s Over.
The star-studded show featured a host of international musicians who performed in honour of the victims, including Katy Perry, Justin Bieber, Little Mix, Pharrell Williams, Coldplay, Black Eyed Peas and a surprise performance by Liam Gallagher
One Love Manchester is now available on BBC iPlayer.