Stewart was born in Los Angeles, California, on April 9, 1990. Both of her parents work in the entertainment industry. Her American father, John Stewart, is a stage manager and television producer who has worked for Fox and on the Comedy Central show @midnight. Her Australian mother, Jules Mann-Stewart, is originally from Maroochydore, Queensland. She is a script supervisor and also directed the 2012 film K-11. Stewart has an older brother, Cameron B. Stewart, and two adopted brothers, Dana and Taylor. Stewart attended local schools until the seventh grade. As she became more involved in acting, she continued her education by distance until completing high school.

Stewart next starred alongside Juliette Binoche and Chloë Grace Moretz in Olivier Assayas’ Clouds of Sils Maria. The film premiered at the 2014 Cannes Film Festival. Her performance in the film garnered critical acclaim. Todd McCarthy of The Hollywood Reporter said that “Stewart’s habitual low-keyed style, which can border on the monotone, functions as effectively underplayed contrast.” Peter Debruge of Variety praised her, saying that “Stewart is the one who actually embodies what Binoche’s character most fears, countering the older actress’ more studied technique with the same spontaneous, agitated energy that makes her the most compellingly watchable American actress of her generation.” Robbie Collin of the Daily Telegraph praised her, saying “…it’s Stewart who really shines here. Valentine is probably her best role to date: she’s sharp and subtle, knowable and then suddenly distant, and a late, surprising twist is handled with a brilliant lightness of touch.” For the performance, Stewart won the César Award for Best Supporting Actress, becoming the first American actress to receive a nomination in thirty years. She is the second American winner after Adrien Brody, who won the César Award for Best Actor in 2003.

On November 16, 2007, Summit Entertainment announced that Stewart would play main character Isabella “Bella” Swan in the film Twilight, based on Stephenie Meyer’s bestselling vampire romance novel of the same name. Stewart was on the set of Adventureland when director Catherine Hardwicke visited her for an informal screen test, which “captivated” the director. She starred alongside Robert Pattinson, who plays Edward Cullen, her vampire boyfriend. The film began production in February 2008 and finished filming in May 2008.

Stewart appeared as teenager Lucy Hardwicke in In the Land of Women (2007), a romantic drama starring Meg Ryan and Adam Brody. The film, as well as Stewart’s performance, received mixed reviews. That same year, Stewart had a small role in the Sean Penn-directed adaptation Into the Wild. For her portrayal of Tracy – a teenage singer who has a crush on young adventurer Christopher McCandless (played by Emile Hirsch) – Stewart received mixed reviews. While Salon.com considered her work a “sturdy, sensitive performance”, and the Chicago Tribune noted that she did “vividly well with a sketch of a role”, Variety’s critic Dennis Harvey said, “It’s unclear whether Stewart means to be playing hippie-chick Tracy as vapid, or whether it just comes off that way.” The film received Screen Actors Guild nomination for Outstanding Performance by a Cast in a Motion Picture. After Into the Wild, Stewart had a cameo appearance in Jumper and also appeared in What Just Happened, which was released in October 2008. She co-starred in The Cake Eaters, an independent film that has been screened only at film festivals. Both the film and Stewart’s performance received many positive reviews. Critic Bill Goodykoontz from The Arizona Republic said that Stewart “really shines…. She excels at both aspects of the performance, giving Georgia a strength that defies any sort of pity one might feel for her, without letting us forget her vulnerability”.

Twilight was released domestically on November 21, 2008. Stewart’s performance garnered mixed reviews with some critics describing her as “the ideal casting choice” and praising her for conveying “Bella’s detachment, as well as her need to bust through it;” others criticized her acting for being “wooden” and lacking variety in her facial expressions, which they described as “blank”.

She was nominated four times, three consecutive years (2003–2005) and in 2008 for the Young Artist Award.

In 2008 she ranked number 17 on Entertainment Weekly’s “30 Under 30″ the actress list, and she was also named the Movie Fanatic’s Hottest Young Actress, and she also was ranked number 9 on Moviefone’s “The 25 Hottest Actors Under 25”.

In 2009, Stewart starred in The Yellow Handkerchief, which debuted at the Sundance Film Festival and was released into theaters in 2010 by Samuel Goldwyn Films. She also starred alongside James Gandolfini in Welcome to the Rileys, which premiered at the Sundance Film Festival in January 2010.

In 2010, Stewart portrayed rock star Joan Jett in The Runaways, a biographical film of the titular band from writer-director Floria Sigismondi. Stewart met with Jett over the 2008–2009 New Year to prepare for the role; she prerecorded songs in a studio for the film. She received praise for her performance: the Metro Times wrote, “It turns out that Stewart is actually really good at capturing Jett’s icy, tough-but-cool girl swagger, adding the needed touches of vulnerability that transform it into a pretty terrific performance… Stewart is a genuine rock star here.” Also, A. O. Scott of The New York Times noted “Ms. Stewart, watchful and unassuming, gives the movie its spine and soul.” The same year, Stewart was listed as the highest-earning actress in Vanity Fair’s “2010’s Top Hollywood Top Earners List”, with an estimated earning of $28.5 million for her film roles in 2010. She won the BAFTA Rising Star Award in 2010 and was awarded the Milan International Film Festival Award for Best Actress in 2011 for Welcome to the Rileys (2010).

She was named “Stonette of the Year” by High Times in 2010.

The fourth Twilight film, Breaking Dawn – Part 1, was released on November 18, 2011. Despite the film receiving mixed to negative reviews, Stewart’s performance was praised. Gabriel Chong called Stewart’s work “mesmerising” and said that she “makes [Bella’s] every emotion keenly felt that runs the gamut from joy, trepidation, anxiety, distress and above all quiet and resolute determination.” The Village Voice’s Dan Konis said Stewart “beautifully underplays” the role. Certain critics found Stewart’s chemistry with Pattinson lacking and said that the relationship between their characters came off like a “charade” onscreen, or that none of the three leads was convincing in their role.

On December 6, 2011, Stewart was named number one on Forbes magazine’s list of “Hollywood’s Best Actors for the Buck”. On January 13, 2012, she became the face of a new unnamed Balenciaga perfume; in June, its name was promoted as “Florabotanica”.

Stewart was listed as the highest-earning actress in the Vanity Fair “Hollywood Top Earners List of 2010”, with estimated earnings of $28.5 million. In 2011, she was named number one on Forbes’ list of “Hollywood’s Best Actors for the Buck”. Forbes also ranked her as the world’s highest-paid actress in 2012, with total earnings of $34.5 million.

She concluded the role of Bella Swan in the final installment in the series, Breaking Dawn – Part 2, in November 2012. The film, despite mixed critical reception, was a box office success, grossing nearly $830 million worldwide, becoming the 40th highest-grossing film, and the highest-grossing film of the Twilight series. On Rotten Tomatoes, the film currently holds a 48% rotten rating, based on 174 reviews with the consensus stating: “It is the most enjoyable chapter in The Twilight Saga, but that’s not enough to make Breaking Dawn Part 2 worth watching for filmgoers who don’t already count themselves among the franchise converts.”

According to Forbes, Stewart was the world’s highest-paid actress in 2012, with total earnings of $34.5 million. She earned $12.5 million each for the last two installments in the Twilight series, including royalties.

Stewart dated her Speak co-star Michael Angarano until early 2009. In mid-2009, she started dating her The Twilight Saga co-star Robert Pattinson. In July 2012, she was photographed having an affair with her Snow White and the Huntsman director Rupert Sanders. Sanders, who was 19 years older than Stewart and married at the time, issued a public apology for the affair, as did Stewart. Pattinson and Stewart split, but reconciled in October 2012. The couple eventually broke up for good in May 2013. In mid 2013, Stewart started dating visual effects producer Alicia Cargile. They had separated by early 2016, resumed dating in mid 2016 but separated again by late 2016. From late 2016, she was in a relationship with British-New Zealand model Stella Maxwell until their breakup in late 2018. They resumed dating in mid 2019 but had separated again by August 2019. She is currently in a relationship with screenwriter Dylan Meyer.

In 2012, Stewart signed her Breaking Dawn – Part 2 dress and gave it to a CharityBuzz auction benefiting the Robin Hood Foundation’s Sandy Relief Fund, which provides long-term support to those affected by Hurricane Sandy. In 2013, she reportedly raised $500,000 for the Sandy relief effort by meeting with an unnamed “Middle Eastern Prince” for 15 minutes. In 2016, she participated in building a school in Nicaragua through the buildOn campaign. The goal being to give children the opportunity to become educated in a safe space and to break the cycle of poverty and illiteracy.

On February 24, 2013, she presented at the 85th Academy Awards with fellow actor Daniel Radcliffe. On December 11, 2013, Chanel announced that Stewart was its “new face” for a Western-inspired fashion collection. The campaign has been shot by Karl Lagerfeld and was released online in May 2014. In 2014, Balenciaga released a new fragrance, Rosabotanica, with Stewart remaining the face of the brand. She was ranked No. 3 on Forbes’ highest-paid actress in 2013, with a total earning of $22 million, #10 in 2014 with $12 million, and #9 in 2015 with $12 million.

Camp X-Ray, her first film of 2014, was premiered at the 2014 Sundance Film Festival on January 17. Her performance as a young soldier stationed at Guantanamo Bay detention camp garnered rave reviews from critics. David Rooney of The Hollywood Reporter called it “her best screen work to date [playing the role of] an inexperienced military guard”, while Xan Brooks of The Guardian said, “It’s a role that reminds us what a fine performer she was in the likes of Into the Wild and Adventureland.”. In 2014, she appeared in the music video for Jenny Lewis’ “Just One of The Guys”, and in The New York Times short movie 9 Kisses.

Stewart appeared alongside Julianne Moore in Still Alice, a drama film that premiered at the 2014 Toronto International Film Festival. Her performance received praise from critics. Peter Travers of Rolling Stone called her “wonderfully vibrant and contentious” and said: “Even when Still Alice sometimes slips into sentiment, Moore and Stewart are funny, fierce and glorious. In 2015, she was named #1 on Glamour’s list of “Best Dressed Women”. She appeared in Tim Blake Nelson’s Anesthesia, an indie drama about a group of New Yorkers, which was released on January 8, 2016 by IFC Films. She costarred with Jesse Eisenberg again in American Ultra, which was filmed from April to June 2014, and was released on August 21, 2015. In December 2015 she starred in Once and Forever, which was directed by Karl Lagerfeld.

Stewart co-starred along with Nicholas Hoult in Drake Doremus’ futuristic love story Equals which was released on July 15, 2016. Filming took place in Japan and Singapore from August to September 2014. In 2015, Stewart was confirmed to join Certain Women directed by Kelly Reichardt; the film was released on October 14, 2016. In 2016, she starred in the Woody Allen film Café Society, opposite Steve Carell and Jesse Eisenberg, marking her third collaboration with the latter; it was released on July 15, 2016. Stewart also reunited with Clouds of Sils Maria director Olivier Assayas to headline his film Personal Shopper, a ghost story that takes place in the fashion industry. She also co-starred in Ang Lee’s war drama Billy Lynn’s Long Halftime Walk, which was released on November 11, 2016. In December 2016, Stewart appeared in the official music video for the Rolling Stones’ single “Ride ‘Em on Down”.

In 2016, Stewart became the youngest actress to be an honoree at the New York Film Festival. In the same year, Stewart was also an honoree at Elle’s Women in Hollywood Awards alongside Amy Adams, Felicity Jones, Anna Kendrick, Aja Naomi King, Helen Mirren, and Lupita Nyong’o.

On May 2, 2016, it was announced that Stewart would make her directorial debut with a short film titled Water for female-focused digital publisher Refinery29. The short will be part of their ShatterBox Anthology. In July 2016, it was confirmed that Stewart’s short film will be titled Come Swim in an interview with Philippine Daily Inquirer. It had its world premiere at the Sundance Film Festival in January 2017. During the 2017 Sundance Film Festival, Stewart revealed that her next short film will be about gun control.

In 2017, Stewart coauthored a computer science preprint about the use of Neural net techniques in the making of her short film Come Swim. That same year, Stewart hosted Saturday Night Live for the first time with musical guest Alessia Cara. and was invited to join the Academy of Motion Picture Arts and Sciences

In an interview with The Guardian, she stated that she was bisexual, saying, “You’re not confused if you’re bisexual. It’s not confusing at all. For me, it’s quite the opposite.” Similarly, in an interview with Harper’s Bazaar in August 2017, she stated that she was open to dating men again, saying, “I want to try everything.” Stewart had also discussed the perceived impact of her sexuality on the success of her career, saying that she had been warned not to be public with her girlfriend so that someone could cast her in mainstream roles. She said, “I don’t want to work with people like that.”

In 2018, Stewart appeared opposite Chloë Sevigny in Lizzie, about Lizzie Borden, directed by Craig William Macneill, which had its world premiere at the Sundance Film Festival in January 2018. It was released on September 14, 2018, by Saban Films and Roadside Attractions. The film received mixed reviews from critics. She also starred in JT LeRoy, a biopic about Laura Albert, alongside Laura Dern and Diane Kruger. She also appeared in the music video for Interpol’s “If You Really Love Nothing”. She also served as a member of the jury for the official competition of the 2018 Cannes Film Festival.

In 2019, Stewart starred as actress Jean Seberg in Seberg, directed by Benedict Andrews. The film premiered at the Venice Film Festival on August 30, 2019. While the film received mixed reviews from critics, Stewart’s performance received praise. It was released in the United Kingdom on January 10, 2020, by Universal Pictures and in the United States on February 21, 2020, by Amazon Studios, after an awards-qualifying run on December 13, 2019. Time magazine declared her performance the 10th best performance of 2019.

Stewart returned to mainstream Hollywood with starring roles in the action comedy film Charlie’s Angels (2019) and the science fiction film Underwater (2020). Both films were poorly-reviewed by critics, but her performance in the former was well received. Stewart wrote and directed a short film titled Crickets, as part of the anthology series Homemade which follows stories from 18 filmmakers from around the world during the COVID-19 pandemic isolation. It was co-produced by Pablo Larraín’s production company Fabula. The series was released on June 30, 2020 on the Netflix platform.

Stewart will next star in Happiest Season, a LGBT holiday romance film opposite Mackenzie Davis directed by Clea DuVall set for a November 25, 2020, release. She is working on her feature film directorial debut, which will be an adaptation of writer Lidia Yuknavitch’s memoir The Chronology of Water, which she will also write. She is also attached to star alongside Riley Keough in a Netflix television series adaptation of Gina Frangello’s novel A Life in Men, produced by Charlize Theron. and to play Joan Vollmer, the most prominent female member of the Beat Generation, alongside Ben Foster in his untitled directorial debut, an adaptation of William S. Burroughs’ early works and letters. On June 17, 2020, she was cast as Princess Diana in Pablo Larraín’s upcoming film, Spencer, which focuses on Diana’s decision to divorce Prince Charles.

In 2020, she received the Actress of the Decade award by the Hollywood Critics Association.