The musician stood by her longtime friend's side in Martha's Vineyard, Massachusetts, as she wed photographer Matt Lucier at Old Whaling Church in Edgartown, reported People magazine.
Abigail wore a stunning light pink and white gown and Swift was seen helping her with her dress.
The 27-year-old singer wore a burgundy dress, which she paired with a matching lipstick.
A group of children and adults had gathered outside the church, hoping to catch a glimpse of Swift.