On Saturday, Britany Maack – who Swift grew up with in Pennsylvania – wed Benjamin LaManna in Pennsylvania.
The bride and her superstar maid of honor wore dresses by celebrity designer Reem Acra. The bride's hand-embroidered silk taffeta ball gown was completed with a matching hand-embroidered cathedral veil. Swift's dress was a blush pink chiffon cap sleeve gown with a hand-embroidered bodice.
Swift shared a group shot from the wedding, writing, "I met her when I was 10 days old, and him in kindergarten. Now they're married and I'm the happiest maid of honor ever. Congratulations @britmaack and Ben!"
"I've never been a maid of honor before. This is my first time, and it's really, really important to me because this is my best friend, who I've known since I was born. And she's marrying someone I've known since I was 4," Swift told PEOPLE in May.
She added that they chose the designer because she was a "favorite" of theirs.
"Reem does the most amazing bridal designs, and Britany and I were looking through Vogue, and she pointed to this one gown, and I was like, 'I wonder if we could go to the showroom…,' " she added.
She and Mack popped by Acra's NYC showroom over the summer and Swift called the experience "the best day ever. It was so amazing."