Finneas O’Connell and Claudia Sulewski have officially turned a relationship that began on a dating app into a marriage celebrated in Montecito, California.

The longtime couple tied the knot on Saturday, Aug. 29, marking the latest chapter in a love story that has stretched across eight years, several creative collaborations and a romantic engagement that Finneas admitted was much harder to keep secret than he expected.

The wedding also included one especially meaningful family moment: Finneas’ younger sister, Billie Eilish, officiated the ceremony.

For the 29-year-old producer and the 30-year-old actress, host and skincare founder, the weekend brought together family, friends and a guest list filled with familiar names from entertainment.

But the road to the altar had started much more quietly.

Their Relationship Began With a Dating App Match

Finneas and Sulewski first met through a dating app in 2018.

The connection apparently made an impression almost immediately.

In 2019, Finneas revealed that he began writing his song “Claudia” within hours of meeting Sulewski. He even sent parts of the song to her that same night.

That early gesture became an unusually fitting beginning for a relationship in which music and creativity would continue to play an important role.

Finneas, who has become widely known as a songwriter and producer and for his work with Billie Eilish, continued to draw inspiration from Sulewski as their relationship developed.

Several years later, she became the muse for another song.

In 2022, Finneas released “Mona Lisa, Mona Lisa,” with Sulewski not only appearing alongside him in the music video but also directing it.

Their relationship had become both romantic and creative, with the two regularly finding ways to work together while building their life as a couple.

Finneas Proposed After Seven Years Together

By September 2025, Finneas was preparing for a much bigger surprise.

After seven years of dating, he proposed to Sulewski during a romantic sunset moment.

The proposal featured a cushion-cut diamond engagement ring, and the couple later announced the news together on social media.

Their simple message included the date Sept. 22 and a promise of “forever and ever.”

For Sulewski, the proposal may have looked peaceful and romantic.

For Finneas, the weeks leading up to it were apparently anything but relaxed.

Soon after the engagement, he spoke about how difficult it had been to keep the plan hidden.

The secret was a happy one, but he joked that the experience taught him he would probably be terrible at committing crimes because even keeping good news to himself caused enormous stress.

He had been carrying the proposal plan for weeks, thinking about every detail and trying to make sure nothing spoiled the surprise.

Once Sulewski said yes, he felt an enormous sense of relief.

He Wanted the Proposal to Be Right

Finneas later explained that the pressure came from caring deeply about getting the moment right.

He had spent months thinking about different elements of the proposal and admitted that there were nights when the planning kept him awake.

When the day finally arrived, however, the nervousness gave way to happiness.

Everything had worked.

Sulewski accepted.

And after years together, they could begin planning their wedding.

Finneas also made it clear early on that he did not intend to dominate those plans.

Instead, he wanted Sulewski to have a major role in shaping the celebration.

He joked that his job would essentially be to act as her “hype man.”

If she wanted his opinion between several options, he was happy to give it. But his larger priority was making sure she loved the final result.

That attitude would eventually lead to a wedding weekend filled with carefully chosen details — including several different bridal looks.

Claudia Wore Four Oscar de la Renta Looks

Sulewski wore four different Oscar de la Renta designs across the wedding weekend.

Each look corresponded to a different part of the celebration.

There was one for the rehearsal dinner, another for the wedding ceremony, a separate look for the first dance and reception, and a fourth for the after-party.

The multiple outfits reflected how the wedding unfolded not as one single event but as an entire weekend of celebrations.

For Sulewski, who is also the founder of CYKLAR Skincare, the fashion choices became one of the most visible elements of the occasion.

But the ceremony itself included a detail that was even more personal.

Billie Eilish Officiated Her Brother’s Wedding

Rather than having a stranger or distant officiant lead the ceremony, Finneas and Sulewski turned to someone who has been deeply connected to both his personal life and professional career.

Billie Eilish officiated the wedding.

Finneas and Eilish have spent years creating music together, forming one of the most successful sibling partnerships in modern pop music.

Now Eilish had a different role in her brother’s life: helping officially mark his marriage.

The moment added a strong family element to an already personal celebration.

Eilish was also joined at the wedding by her boyfriend, Nat Wolff.

The Guest List Included Plenty of Familiar Faces

The Montecito celebration brought together a number of well-known guests.

Among those attending were Nina Dobrev, Dax Shepard, Kristen Bell, Emma Chamberlain, Rachel Sennott, Stassie Karanikolaou, Jason Sudeikis and Carter Gregory.

Justin Bieber and Hailey Bieber were also among the guests.

The celebrity-filled gathering reflected the worlds Finneas and Sulewski have moved through during their years together — music, acting, online media and entertainment.

Still, the story behind the wedding remained grounded in a relationship that began long before the ceremony.

Before the designer outfits, celebrity guests and Montecito setting, there was a dating app match.

Then came a song written within hours.

Then seven years together before a proposal.

And then nearly another year before the wedding itself.

A Love Story Built Alongside Their Careers

Finneas and Sulewski’s relationship has unfolded while both have developed careers of their own.

Finneas became known for his production work and his creative partnership with Eilish.

Sulewski built a career as a host and actress before also launching CYKLAR Skincare.

Throughout that time, their relationship frequently crossed into their creative work rather than remaining completely separate from it.

She inspired songs.

They appeared together in music projects.

She directed.

He wrote.

That history makes their wedding feel less like a sudden celebrity milestone and more like the continuation of something they had already been building for years.

Their engagement announcement in 2025 promised “forever and ever.”

Less than a year later, they gathered in Montecito and made that promise official.

After eight years together, Finneas and Claudia Sulewski are now husband and wife — with four wedding looks, a star-filled guest list and Billie Eilish standing beside them in one of the ceremony’s most important roles.