The 28-year-old entertainer, who will star in the upcoming season of "American Horror Story", wore a floor-length violet dress to the Big Easy nuptials.
She wore minimal makeup and kept her blonde locks down, reported Us magazine.
"Watching your best friend get married, these are the specialist times in my life. Seeing happiness in the lives of all my friends," Gaga captioned a photo of her pink high heels on March 18.
The following day, she wore a black dress while chatting it up with her girl friends.