Born in Los Angeles in 1997, Finneas Baird O'Connell grew up in a creative family; his parents are actress/screenwriter Maggie Baird and actor Patrick O'Connell. His sister, Billie Eilish (full name Billie Eilish Pirate Baird O'Connell), is four-and-a-half-years younger. A child actor, he started writing and recording his own music around age 12. Meanwhile, he made his film debut alongside Cameron Diaz in 2011's Bad Teacher, and in 2013, he appeared on the soundtrack of the music-themed film drama Life Inside Out, in which he starred alongside his mother. Parts on Modern Family and Aquarius followed, and in 2015, he appeared as the recurring character Alistair on the sixth season of Glee. Early the next year, his guitar pop group the Slightlys issued their debut single, "Desperate Measures." Later in 2016, Eilish had her big breakthrough with the Finneas-produced "Ocean Eyes," a song that he had originally written for his band. After garnering tens of millions of streams, it eventually reached number 84 on the U.S. Hot 100.
The siblings continued their successful professional partnership, with Finneas co-writing and producing Eilish's debut EP, Don't Smile at Me, which arrived on Interscope in 2017. That year, their stand-alone single "Bored" was included on the soundtrack to the Netflix series 13 Reasons Why. By then a bona fide pop superstar, Eilish's 2019 full-length debut, When We All Fall Asleep, Where Do We Go?, topped the Billboard 200. It was produced and co-written by Finneas. By the end of the year, he had also found work producing songs for the likes of Selena Gomez and Camila Cabello.
In October of 2019, Finneas presented his full-length solo debut, Blood Harmony. A set of intimate relationship songs released on the OYOY label, it led to an appearance in the Top Five of Billboard's Next Big Sound chart. That November, he collected five Grammy Award nominations for his work on Eilish's debut album, including Record, Album, Song, and Producer of the Year (in addition to Best Engineered Album, Non-Classical). In 2022, O'Connell composed the score for the Megan Park-directed school shooting drama The Fallout. ~ Marcy Donelson, Rovi