Eilish, who recently dropped her latest album "Happier Than Ever," has been known for her signature carpet looks -- read loose-fitting pants and jackets.
However, the 19-year-old upped the ante this year as she dazzled with the gown, designed by Oscar de la Renta, which makes it the first time Billie has worn the designer on the red carpet.
But reportedly, Eilish had one condition for agreeing to work with them -- don't use fur anymore. And they agreed!
The seven-time Grammy award-winning artist, the belle of the ball, told Vogue: "It was time for this. I feel like I've grown so much over the last few years."
Born in Los Angeles, Eilish has been nominated for the Grammy Awards 10 times in the past.
The artist’s track record so far speaks for their young career — Five tracks in top 10 out of the 30 songs that ranked on Billboard's Hot 100 chart, including the no. 1 hits Bad Guy and Therefore I Am.
Meanwhile, along with Naomi Osaka, Timothée Chalamet and Amanda Gorman, Eilish is set to co-hosting the event, which returns after being cancelled last year due to the pandemic.
Among other walkers was Keke Palmer in a stunning, earth-tone body hugger with a train, while Ilana Glazer took her moment on the steps in feathery long sleeves and a creamy, high-neck gown. Both were hosts of Vogue's live stream of the gala.
Yara Shahidi wore a silver custom Dior complete with a headpiece. She said she was inspired by Josephine Baker.
Meanwhile, Dan Levy took the party's theme to the extreme in a blue confection from Loewe. It had, according to the brand, “printed leg of mutton sleeves" on a polo shirt with an applique of two men kissing.
Also Read: Best dressed Met Gala couples of all time
The gala, which raises money for the museum's Costume Institute, was pushed last year from its traditional May berth and morphed this year into a two-part affair. It coincides with the opening of “In America: A Lexicon of Fashion,” the first of a two-part exhibition at the Met's Anna Wintour Costume Center.