"I've been wanting to tell you this for a really long time," Swift said in a video Thursday addressed to her fans.
"So I'm really excited, I hope you are too, and I can't wait to see you, can't wait to see them, really excited just about the whole thing in general."
Cabello, a former member of Fifth Harmony whose first debut album Camila debuted in January with the hit-single "Havana," thanked Swift on Twitter.
"On every level, this is a dream come true, thank you Taylor for having me from the bottom of my heart, i love you so much!!!!!!!!" she said.
Charli XCX, known for the song "Boom Clap," also shared her gratitude on Twitter, stating, "I am so excited thank u Taylor for having me."
The Reputation stadium tour, in support of Swift's latest album of the same name, begins May 8 in Glendale, Ariz., at the University of Phoenix Stadium before wrapping up October 6 in Arlington, Texas, at the AT&T Stadium.
The pop star will also be performing in Seattle, Denver, Chicago, Philadelphia, Cleveland, Toronto, Atlanta, Miami, New Orleans and Houston, among others cities.
Cabello has her first-ever solo tour set to kick-off April 9 in Vancouver, B.C., and will bring the North American portion to a close May 4 in New York.
She will also be performing four dates in the U.K. in June.
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