"I hope you don't mind that I planned something special," Swift told the crowd before bringing Morris on stage. "I get to bring out somebody who I am - I think I can safely categorize myself as a superfan of this artist. I listen to [Morris' Hero album] over and over and over, and I can't wait to see what she does next."
The two artists (and new friends) belted out Morris' hit "The Middle" on the last U.S. stop on Swift's Reputation Tour.
Swift shared her excitement over the collaboration on her Instagram, adding that Morris' Texas fans are proud of their hometown hero.
"Maren is from Arlington TX and judging from the deafening screeches of joy from the crowd, they are proud of her," Swift wrote. "So so grateful this happened, I was so happy I was really just bopping like an 8 year old alone in my room."
Morris was clearly thrilled to share the stage with Swift. She shared a photo from Swift's tour rehearsal on her Instagram captioned with "'Did we just become best friends?' Got to play my hometown stadium with this woman. Thank you @taylorswift. Congratulations on a mind-blowing tour."
Swift will wrap up the Reputation Tour on Nov. 21 in Tokyo, Japan.
Morris is currently working on her sophomore album. She'll be honored at the 2018 "CMT Artists of the Year" ceremony. Fellow honorees include Carrie Underwood, Miranda Lambert, Kelsea Ballerini, Little Big Town's Kimberly Schlapman and Karen Fairchild and Lady Antebellum's Hillary Scott. Loretta Lynn will receive the Artist of a Lifetime award. The special will air Oct. 17 at 7 p.m. CT.