Gaga kicked off the event by giving an emotional speech.
"As my LGBT fans and friends always said to me, I knew Lady Gaga when…well look who the star is now," she began. "Now, I get to say that I knew you when. Now I get to say I knew you when you suffered, when you felt unequal, when you felt there was nothing to look forward to. I knew you then, and I knew you when, but I really know you now."
The "Born This Way" singer followed her speech with an a cappella rendition of the "Star-Spangled Banner," during which she held an LBGT flag.
Friday night's performance was one of the first events attended by Gaga after her hip surgery.