Born on Nov. 18, 1974 in Springfield, MA, Sevigny was raised in Darien, CT by her father, H. David, an accountant and interior decorator, and her mother, Janine. Though part of a tony New England community that provided all the advantages, Sevigny grew up feeling like an outsider. While attending Darien High School, she chose to avoid the school’s renowned theater program, showing no interest whatsoever in getting involved. Supported by her family, but stifled in her community, she set out for Manhattan as a teenager and joined the throng of skater kids that congregated in Washington Square Park. It was here that she met Harmony Korine, who would go on pen the screenplay for Sevigny's acting debut, "Kids" (1995), as well as write and direct the films "Gummo" (1997) and "Julien Donkey-Boy" (1999), which would also feature the actress. Cast initially in a small role in "Kids,” Sevigny landed the part of Jennie just prior to filming. Marking her film debut in Larry Clark’s controversial helmed feature proved advantageous for the ingénue, who made a lasting impression with her gentle portrayal of a young teenager who learns she is HIV positive.

With nothing but raw talent, Sevigny emerged from her “Kids” experience with a bright future in acting. She followed up the next year with a role as the precocious young assistant and brief love interest of Steve Buscemi's ice cream man in "Trees Lounge” (1996). In 1997, she took on a small role as an albino girl in "Gummo,” Korine's bleak look at small town ruin. Sevigny, who had experience making her own clothes as a high school student, also designed the costumes for the non-narrative feature. Lucky for her, Sevigny emerged virtually unscathed by critiques of the film's harsh outlook and detached approach. Excited to work with famed German director Volker Schlondorff, she followed with "Palmetto” (1998), an uninspired modern noir that was disappointing for the actress and audiences alike. She fared better with a starring role in Whit Stillman's "The Last Days of Disco" (1998), utilizing the mores and manners of her posh upbringing in her portrayal of a new Hampshire College graduate making her way in New York City in the early 1980s. Sevigny stood apart from the rest of the cast in the film, with her low-key portrayal lending an added dimension to her character's separation from the regular cast of Stillman acerbics.

That same year, Sevigny took on her first stage role in the New York theater production of "Hazelwood Jr. High," a real-life drama of a vicious teenage murder, eerily staged at middle school performance space I.S. 70. Sevigny gave a chilling performance as the unemotional sociopath who dabbles in devil worship and ups the preteen angst ante to tragic effect in Rob Urbinati's uneven play. Meanwhile, just as likely to be seen on the pages of Vogue as Premiere, Sevigny enchanted trend watchers with her unique sense of style and irreverent attitude towards fashion. Singled out by author Jay McInerney with a seven page feature in The New Yorker that proclaimed her the “It Girl” of the moment, Sevigny was a pop phenomenon before she established a solid acting career. Her status as darling of the underground celebrity set threatened to overshadow her acting in the late 1990s, with the young up-and-comer getting more notice for her clothing choices and lifestyle than her film work.

In 1999, Sevigny managed to transcend hipster labels with a show of formidable talent in a trio of big screen releases. She effectively essayed a pregnant teen engaging in an incestuous relationship with her schizophrenic brother (Ewen Bremner) in Korine's daring Dogma '95 feature "Julien Donkey-Boy," and offered a memorable supporting turn as an ill-prepared working mother who clashes with school nurse and town outcast Alice Goodwin (Sigourney Weaver) in Scott Elliott's powerful drama "A Map of the World.” Most notable was her turn as Lana, the love interest of a captivating man (Hilary Swank) hiding his biological femaleness in Kimberly Peirce's remarkable feature "Boys Don't Cry” (1999). Powerful performances abounded in the finely crafted film, with Sevigny proving more than capable of holding her own opposite eventual Oscar winner Swank. Her skilled portrayal was a pleasant surprise for many moviegoers. The actress' remarkable onscreen magnetism and charisma brought added magic to the character, and her understated but unflinching portrayal earned her a richly deserved Academy Award nomination as Best Supporting Actress.

The following year would see the actress take on a role in Mary Herron's controversy-plagued "American Psycho" (2000), based on Bret Easton Ellis' novel about a stylish businessman (Christian Bale) who brutally tortures and murders for kicks. That same year, Sevigny made her television acting debut in the "1972" segment of "If These Walls Could Talk 2" (HBO, 2000), a lesbian-themed anthology drama in which she played a boyish-dressing woman who falls in love with a more softer-looking collegiate lesbian (Michelle Williams). After a detour appearing in low-profile fare like the French techno thriller "Demonlover" (2002) and a turn as one of the true-life, hard-partying 1980s club kids embroiled in a murder in "Party Monster" (2003), Sevigny reestablished her art-house credentials with a role in director Lars von Trier's "Dogville" (2003). She next delivered a well-executed performance in the critical favorite "Shattered Glass" (2003), playing one of the misguided loyal colleagues of young New Republic journalist Stephen Glass (Hayden Christensen), who partially or entirely falsified over two dozen articles while writing for the magazine.

Sevigny got a massive dose of media attention for her appearance in an otherwise low-budget, avant-garde art film, "The Brown Bunny" (2004), written, directed and starring bad boy auteur – and Sevigny's ex-boyfriend – Vincent Gallo. Appearing as the lost love of Gallo's professional motorcycle racer, the actress courted controversy and infamy when she appeared in a scene in which she fellates Gallo – an explicit act that was shot by remote camera operated by the director. The resultant controversy when the film first screened at Cannes in 2003 was fanned prior to the movie’s release in 2004, when a billboard on L.A.'s Sunset Strip illustrating the film's sex act was taken down after local protests. Despite the scandal – and Sevigny's strong, convincing performance in scenes other than the infamous sequence – the film was largely drubbed as immature, self-indulgent and unaccomplished.

Adopting a more button-downed role, Sevigny was cast in the tragic portion of writer-director Woody Allen's dual-structured "Melinda and Melinda" (2005), playing the former college friend who contributes to the romantic woes of a neurotic, self-destructive woman (Radha Mitchell). She continued appearing in low-budget indies, including small roles in “Manderlay” (2005), Lars Von Trier’s follow-up to “Dogville” (2003), and “Broken Flowers” (2005), Jim Jarmusch’s road trip drama about a man (Bill Murray) setting out to find the son he never knew he had. Sevigny then made the rare jump to television, appearing as the “other woman” in the dark comic tale of love and obsession, “Mrs. Harris” (HBO, 2006). Landing her first regular series role, she starred as one of three wives (also Jeanne Tripplehorn and Ginnifer Goodwin) married to a hardware store owner (Bill Paxton) in “Big Love” (HBO, 2006- ), the cable networks much-hyped and controversial series centered on Mormon polygamy. The subject matter aroused both interest and controversy, the latter prompting the producers to put a disclaimer before every episode stating that the Mormon Church banned poly-marriage in 1890. Nonetheless, “Big Love” premiered in March 2006 to good reviews, strong ratings and several award nominations.