The pop superstar has remained out of the public eye since cancelling her US tour and undergoing an operation to treat a hip injury in February, but she was back in action on Friday to kick off New York's Gay Pride events.
Gaga gave a speech about her ongoing fight for gay rights during the rally at Manhattan's Pier 26, telling the crowd: "We are not a niche. We are part, a big giant part of humanity. It's time for us to be mainstream. I demand the rights!"
She also led the crowd in a chant before singing an a cappella version of The Star Spangled Banner, changing the last line to reflect the Gay Pride event, singing: "Oh say does that star spangled, flag of pride yet wave. For the land of the free and the home for the brave (sic)."
Pop superstar Cher also performed during the festivities, which marked the star of Gay Pride Week.