After John announced that his lady love would be joining him, she walked on stage and they shared a sweet smooch before beginning their duet "Who You Love."
Earlier that morning, the pair appeared on Good Morning America, where they discussed how the collaboration came about and John revealed why he was nervous about doing a duet with his girlfriend.
They also premiered the super fun video for the song, which features a bunch of different couples (including Katy and John) riding a mechanical bull.
Check out the video below to see their performance.
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Gallery | Katy Perry and John Mayer