Billie Eilish Channels Marilyn Monroe in Glamorous Gown and Blonde Bob

The musician was the epitome of Old Hollywood glamour on the steps of the Met Monday night.

Billie Eilish is a glamorous goddess at the 2021 Met Gala at the Metropolitan Museum of Art in New York City Monday night. Making her first-ever Met Gala debut as one of the night's co-chairs, Eilish wowed in a voluminous peach tulle gown from Oscar de la Renta. Sticking to the theme, "In America: A Lexicon of Fashion," Eilish wowed in an Old Hollywood-inspired look, complete with a soft, blonde bob.

Eilish agreed to wear Oscar de la Renta to the Met Gala under the condition that the fashion house will now go completely fur free. "It was an honor to wear this dress knowing that going forward Oscar de la Renta will be completely fur-free!!!!" Eilish shared on Instagram.

ET's Rachel Smith spoke with the musician on the Met steps. Eilish said she's channeling Marilyn Monroe "a little bit." 

"It's like the most insane honor you would not believe. I feel like I'm in a dream. I feel like I'm tripping," Eilish said of co-chairing the evening. 

Dimitrios Kambouris/Getty Images for The Met Museum/Vogue

The "Happier Than Ever" singer's brother and collaborator Finneas, who wore an all-red ensemble with a matching face mask, joined the conversation. 

"It was fun. Everybody at the hotel was running around all stressed, and I'm like, 'This is a party,'" Finneas said. 

Mike Coppola/Getty Images

The theme of this year's Met Gala is said to be an exploration of the nation’s sartorial identity and a deep dive into American ingenuity. According to the press release, the exhibition opens Sept. 18 and will highlight "everything from the luxe ease of Halston's '70s glamour to Rodarte's ethereal edge and Kerby Jean-Raymond's powerful political vision for Pyer Moss."

It was announced in May that Eilish would be serving as a co-chair for the 2021 Met Gala alongside actor Timothee Chalamet, poet Amanda Gorman and tennis pro Naomi Osaka.

"Each of the night’s co-hosts has made their mark on fashion," the Costume Institute said in a press release. "Eilish’s willingness to embrace an aesthetic as innovative as her music has pushed emerging brands into the limelight and challenged old rules about how a pop star should dress."

The 2021 and 2022 Met Galas will both be themed around America. Part Two, taking place on May 2, 2022, is titled In America: An Anthology of Fashion.

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