The 29-year-old singer was rumoured earlier on Saturday (16Apr16) to be performing later that day, and she hit the stage to sing an emotionally charged version of Zedd's track True Colours.
She was reported to be involved with the song before he released it on his second album in May last year (16), but the artist singing the vocals ended up being an uncredited vocalist named Tim James, editors at JustJared.com report.
She teased her fans with a photo on Instagram on Saturday of her in what looked like a private jet, with the caption, "4 hours and counting. Somewhere over America. Eeek!"
Back in February, Zedd reached out to Kesha via Twitter, and offered the singer help. "Very very sorry to hear about the whole situation. I'll be happy to produce a song for you if you want my help," he wrote.
Earlier this year, Kesha launched an appeal to be released from her Sony contract, claiming music producer Lukasz Sebastian Gottwald, known as Dr. Luke, had sexually assaulted the singer. A court recently ruled she cannot be released from her contract.