Vice President Joe Biden also took the stage to speak out against sexual violence.
Lady Gaga took the stage to make a powerful statement at the Oscars, joining forces with a group of sexual assault survivors to deliver a heart-wrenching performance.
Gaga performed her Academy Award-nominated song "Til It Happens to You," co-written with Diane Warren for the documentary The Hunting Ground, following remarks from Vice President Joe Biden.
"Despite progress over the last few years, too many women and men on and off campuses are still victims of sexual abuse," Biden told the audience. "Tonight, I'm asking you to join millions of Americans including me, President Obama, the thousands of students I've met on college campuses, and the artists here tonight, to take the pledge, a pledge that says I will intervene in situations when consent has not or cannot be given. Let's change the culture!
"We must and we can change the culture so that no abused woman or man like the survivors you will see tonight, ever feel they have to ask themselves, 'What did I do?'" he continued. "They did nothing wrong."
Biden has been a longtime advocate against sexual assault and domestic violence, launching the "It's On Us" campaign in September 2014. The Obama administration described the cause as a "new public awareness and action campaign designed to prevent sexual assault at colleges and universities, change the culture on our own campuses and better engage men in this effort." A public service announcement for the cause featured appearances from Jon Hamm, Kerry Washington, Questlove and Mayim Bialik.
Dressed in all white, Gaga performed "Til It Happens to You" at a large white piano on a dimly lit stage. Towards the end of the performance, she was joined on-stage by a group of sexual assault survivors with various mantras, including "Not Your Fault," "Unbreakable," and "Survivor," written on their arms. The set garnered a standing ovation and moved audience members including Kate Winslet and Rachel McAdams to tears.
Though Sam Smith's "Writing's on the Wall" from Spectre ended up taking home the Oscar, Gaga dedicated her nomination last month to survivors of sexual assault. The cause is particularly personal for Gaga, who previously revealed that she was raped at 19 years old.
Earlier on Sunday, Gaga opened up about how her own experience with sexual assault impacted her relationship with fiance Taylor Kinney.
"I never thought anyone would ever love me because I felt like my body was ruined by my abuser," she wrote on Instagram. "But he loves the survivor in me. He's stood by me all night proud and unashamedly. THATS a real man."
In recent weeks, Gaga has thrown her support behind fellow singer-songwriter Kesha as she faces legal turmoil surrounding a lawsuit against producer Dr. Luke. Kesha has accused Dr. Luke (real name: Lukasz Gottwald) of drugging and raping her over a decade ago. Dr. Luke has denied all wrongdoing.
"I'll be thinking of u 2nite," Gaga tweeted at Kesha on Sunday afternoon. "This is not over we'll stand by u until you are free to live a HAPPY life. Everyone deserves that."
Earlier this month, a judge denied Kesha's preliminary injunction request to be let out of her contract with Dr. Luke and Sony Music's Kemosabe Records.
PHOTOS: Oscars 2016 Fashion Trend: See Lady Gaga and More Expertly Rock White Dresses
Sunday marked a return to the Oscars stage for Gaga, who offered up a stunning serenade in honor of The Sound of Music's 50th anniversary last year. Dressed in a dreamy pink gown, Gaga sang her heart out in a medley of "The Sound of Music," "My Favorite Things," "Edelweiss" and "Climb Ev'ry Mountain." See the flashy performance in the player below.