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.
Airport security guard dives to catch tumbling toddler [VIDEO]
Short Hills Mall shooting victim was protecting wife