For one of the show's most moving moments, the 27-year-old hitmaker teamed up with Jodi DiPiazza, a young autistic girl whose progress was documented in a video during the all-star charity event, and the two sang a moving duet of Perry's hit "Firework.
DiPiazza more than held her own, singing and playing piano during an acoustic rendition of the song with the superstar joining in from the chorus on. The performance brought many in the audience to tears, prompted a standing ovation and even choked up the evening's emcee, Jon Stewart.
For her part, DiPiazza got a big hug from Perry and a memory to last a lifetime, while the singer later tweeted, "I will never forget last night. It was the most important moment thus far of what I do."
For those who'd like to join Perry in raising money for autism educational initiatives that help kids like DiPiazza, tune into the Night of Too Many Stars benefit, which airs this Sunday, Oct. 21, at 8 p.m. on Comedy Central.