The show was held to benefit the victims and families involved in the terror attack at Grande's concert in Manchester last month that left 22 people dead and over 100 injured.
In the video, Katy is seen rehearsing for the show, greeting Coldplay's Chris Martin, Justin Bieber, Miley Cyrus and taking pics with Niall Horan. The singer also does an interview right before taking the stage.
"I'm here to give love," Perry says. "I love Ariana and all the fans of music… We're all in this together and that's why I'm here."
The "Swish Swish" singer performed an acoustic rendition of her hit "Part of Me," followed by her empowering single, "Roar." She also paid tribute to the victims with her outfit, which featured actual photos of those affected by the tragic bombing.
According to the British Red Cross, nearly $3 million was raised during the concert alone for the We Love Manchester Emergency Fund.
For more on the One Love Manchester concert, watch below.