Billie Eilish Officiates FINNEAS’ Wedding to Claudia Sulewski: Inside the Celebrity-Filled Ceremony

Billie Eilish had a very important job at her brother FINNEAS’ wedding: she officiated the ceremony.

FINNEAS married longtime girlfriend Claudia Sulewski on Saturday, August 29, in Montecito, California, with Billie standing at the altar to make it official.

The couple celebrated at the iconic San Ysidro Ranch surrounded by family, friends and a seriously star-studded guest list.

Billie Eilish Officiated FINNEAS and Claudia Sulewski’s Wedding

Billie Eilish wasn’t just there as the groom’s younger sister.

The Grammy-winning singer officially served as the wedding officiant as FINNEAS and Claudia exchanged vows, making the ceremony an extra-personal family moment.

Billie and FINNEAS have spent years making music together, winning Grammys and Oscars along the way. Apparently, producing hit records together wasn’t enough — now they can add “wedding officiant” to the sibling résumé.

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Who Attended FINNEAS’ Wedding?

The FINNEAS and Claudia Sulewski wedding guest list included plenty of familiar faces.

Justin and Hailey Bieber, Kristen Bell and Dax Shepard, Emma Chamberlain, Nina Dobrev, Rachel Sennott, Rebecca Black and Jason Sudeikis were among the celebrities spotted at the celebration.

Billie attended with Nat Wolff.

Even FINNEAS and Claudia’s dogs, Peaches and Moose, were part of the festivities.

What Did Claudia Sulewski Wear?

Claudia turned the wedding weekend into a full fashion moment with four custom Oscar de la Renta looks.

According to Vogue, the outfits included separate looks for the rehearsal dinner, wedding ceremony, first dance and reception, and after-party.

For the ceremony, Claudia wore an ivory Oscar de la Renta ball gown featuring a drop-waist silhouette and dramatic scarf detail.

How Long Have FINNEAS and Claudia Sulewski Been Together?

FINNEAS and Claudia first met through a dating app in 2018.

Their connection apparently happened quickly. FINNEAS wrote his song “Claudia” shortly after meeting her, and the couple went on to build both a life and creative projects together.

They announced their engagement in September 2025 before officially tying the knot nearly a year later.

And while Billie Eilish has already collected Grammys, Oscars and some of the biggest hits in pop music, officiating her brother’s wedding might be one of her sweetest accomplishments yet.