Swift, 24, who made a cameo appearance on comedy show 'Saturday Night Live' on August 13, headed to the pre-wedding bash for her fan Gena, reported Contactmusic.
The 'Red' hitmaker had promised to go to her fan's bridal shower since she is unable to attend the wedding next month.
"I had no idea Taylor was coming it was a complete surprise. She's an incredible person and amazing friend... Thank you for making today even more special... You went above and bring my wildest dreams. I can't thank you enough," Gena wrote on Twitter.
Gena, who struck up a friendship with Swift after following her career for several years, posted a series of photographs with her idol.