She continued acting, appearing in major box office pictures such as the romantic comedy, Notting Hill (1999) and M.
Night Shyamalan's psychological thriller, The Sixth Sense (1999).
The film was met with mixed reviews, but the performances of Barton and her co-stars Piper Perabo and Jessica Paré were widely praised.
Barton has since appeared in the comedy remake St Trinian's (2007), the Richard Attenborough-directed drama Closing the Ring (2007) and Assassination of a High School President (2008).She returned to television, starring in the short-lived Ashton Kutcher-produced CW series, The Beautiful Life: TBL (2009).Canby again praised Barton, noting that she "has a sweet gravity as the doomed Emma".In 1996 Barton had a supporting role in Catherine Butterfield's Where the Truth Lies which opened at New York's Irish Repertory Theatre.In 2012, she returned to the stage, performing in the Irish production of Steel Magnolias.
Barton graduated from the Professional Children's School in Manhattan in 2004, and took a summer short course called Acting Shakespeare at The Royal Academy of Dramatic Art in London, in June and July 2006, after he directed her in Closing the Ring.
She began her acting career on the stage, appearing in Tony Kushner's Slavs!
and took the lead in James Lapine's Twelve Dreams at New York City's Lincoln Center.
Barton began acting at the age of eight, co-starring in the Off-Broadway premiere of the 1994 play, Slavs! Vincent Canby of The New York Times praised Barton's "so fine" and "chillingly authoritative" performance.
She appeared in several other Off-Broadway productions, taking a lead role in James Lapine's Twelve Dreams alongside Marisa Tomei at Lincoln Center.
She also starred in Pups, a "Bonnie and Clyde for the MTV generation", alongside Burt Reynolds; along with her co-star Cameron Van Hoy, film critic Roger Ebert called their work in the film "two of the most natural and freed performances I have seen by actors of any age." Barton first appeared on television in 1994, playing a young Corvina Lang in flashbacks in the soap opera All My Children.