Billie Eilish Is Performing a Cover of One of Her Favorite Songs for Oscars In Memoriam

After her historic night at this year's GRAMMYs, the 'Bad Guy' singer is set to take the stage at the Oscars.

Billie Eilish will have an important role at Sunday's 92nd Academy Awards. The 18-year-old singer took to her Instagram the day of the big show to announce that she's performing a cover during the In Memoriam portion of the ceremony.

"Honored to be performing during the In Memoriam segment for the Oscars tonight covering a song I’ve always loved," she wrote.

News of her performance first came after her record-breaking win at the 62nd Annual GRAMMY Awards last month, when Eilish announced the news on Instagram. 

Eilish is one of the only performers of the night who isn't singing a tune that is nominated for an award. Previously announced performers -- including Elton John, Chrissy Metz, Randy Newman, Idina Menzel and Cynthia Erivo -- are performing tunes nominated for Best Song.

Additionally, the Academy of Motion Pictures Arts and Sciences announced that the show will feature a special musical appearance from Questlove, as well as a special segment guest-conducted by Eímear Noone, who will become the first woman to ever conduct the orchestra during an Oscars telecast.

The news came just a few days after Eilish became the youngest artist ever -- and the first female artist -- to ever sweep the top four categories at the GRAMMYs.

ET's Kevin Frazier spoke with Eilish backstage after nabbing her final big win -- and fifth win over all for the night -- and the "Bad Guy" singer had a hard time wrapping her head around the monumental triumph.

"I'm dying, man. I don't know, this s**t is crazy. Who am I?" Eilish said with a dazed laugh. "This is surreal. This is like a dream."

Eilish's brother Finneas O'Connell, her producer and collaborator on her wildly successful debut studio album, When We All Fall Asleep, Where Do We Go?, joined his sister backstage and reflected on the wins.

When asked how a person manages to take in a moment like this, O'Connell said simply, "Oh, you don't."

"A couple years from now we'll be like, 'You remember that one time?'" he added with a laugh. "No, you don't take it in. You just thank and hug all of the people."

This year's Oscars is set to be an emotional one. The Academy announced on Tuesday that the show plans to acknowledge the late Kobe Bryant during the ceremony.

Bryant died the day of the GRAMMYs, along with his 13-year-old daughter and seven others, in a helicopter crash in Calabasas, California. His death was met with on overwhelming outpouring of grief and condolences from people across the world.

Eilish addressed Bryant's death on the red carpet ahead of the GRAMMYs, where she told ET, "God, I mean, I don't know how to put it. Thought it was fake because how can you not? It really makes you think about a lot of things."

"It's hard to talk about. It's so sudden and so random and, like, his beautiful girl," she continued. "I have no words. My condolences. I don't know what to say."

This year's Oscars air live from the Dolby Theatre in Hollywood on Sunday, Feb. 9 at 8:00 p.m. ET / 5:00 p.m. PT on ABC.