The 'Mine' singer introduced Williams to the stage while appearing on the Nashville leg of the tour before performing a version of Paramore's 'That's What You Get'.
Swift told the crowd: "Well, the thing about Nashville, one of the amazing things about it, is that there's so many friends here.
"My friend Hayley has this band called Paramore."
While on tour, Swift has performed covers of local artists including Eminem's 'Lose Yourself' in Detroit and Bon Jovi's 'Livin' on a Prayer' in New Jersey.
Taylor Swift will receive the Harmony Award at the Nashville Symphony's annual gala on December 10 at the Schermerhorn Symphony Centre.
> Paramore debut new track 'Renegade' live - Watch
Watch Taylor Swift and Hayley Williams sing together below: