O'Connell was born in Los Angeles, California, on December 18, 2001. She is the daughter of teacher, actress, and screenwriter Maggie Baird, and construction worker Patrick O'Connell, who worked part-time as an actor, appearing in films like Iron Man (2008). Both her parents are amateur musicians. She is of Irish and Scottish descent. The singer's middle name, Eilish, was originally meant to be her first name, while Pirate (proposed by her brother Finneas, four years her senior) was to be her middle name. She was conceived via in vitro fertilization.She was raised in Los Angeles' Highland Park neighborhood.
