Following a string of film parts as a young child, she rose to prominence at age 10 when she played Olive Hoover in Little Miss Sunshine (2006), for which she received a nomination for the Academy Award for Best Supporting Actress.

[2] Breslin went on to establish herself as a mainstream actress with roles in films such as No Reservations (2007), Nim's Island, Definitely, Maybe (both 2008), My Sister's Keeper, Zombieland (both 2009), Rango (2011), The Call, August: Osage County (both 2013), Maggie (2015), and Stillwater (2021).

[citation needed] The Breslin siblings were raised in Lower East Side, New York[5] in a "very close-knit" household; her father was of Jewish heritage.

[17][18] Meghan Keane of The New York Sun wrote that "the scenes between Mr. Lewis and the charmingly fragile Kira, winningly played by Ms. Breslin, bring a captivating humanity to the film".

[19] Breslin's breakthrough role was in the 2006 comedy-drama Little Miss Sunshine, where she played Olive Hoover, a beauty pageant contestant, the youngest in a dysfunctional family on a road trip.

[23] Her performance was highly praised;[24][25] Claudia Puig of USA Today wrote that, "If Olive had been played by any other little girl, she would not have affected us as mightily as [she] did.

[29] On October 27, 2007, Breslin made her stage debut in the play Right You Are (If You Think You Are) in New York City at the Guggenheim Museum starring in an ensemble cast, including Cate Blanchett, Dianne Wiest, Natalie Portman and Peter Sarsgaard.

[31] Breslin next appeared in the 2007 romantic comedy No Reservations, playing the niece of master chef Kate Armstrong (Catherine Zeta-Jones).

[42] Breslin's performance in the film was praised by critics;[43][44] Joe Morgenstern of The Wall Street Journal wrote that she "carries the event-stuffed story with unflagging grace.

[49] James Berardinelli wrote that Breslin and Vassilieva "display a natural bond one might expect from sisters, and there's no hint of artifice or overacting in either performance.

[54] With previews beginning in February 2010, she made her Broadway debut as Helen Keller in The Miracle Worker at the Circle in the Square Theatre.

[59] Breslin's performance was praised by critics;[60][61][62] Frank Scheck of The Hollywood Reporter wrote that she "well portrays Helen's feral rebelliousness in the play's early sections and is deeply touching as her character's bond with her teacher grows.

[72] In 2013, Breslin also appeared in Haunter in the role of Lisa, a ghost who bonds with a future girl living in her house to stop an evil killing spirit with the help of his many victims.

[77] In July 2012, she was cast in August: Osage County, the film adaptation of the Pulitzer Prize-winning play of the same name, alongside Julia Roberts, Benedict Cumberbatch, and Meryl Streep.

[84][85] She explained that she did not report being raped at the time because she "was in complete shock and total denial", "feared not being believed" by the police, worried about revenge by the assailant if he found out and concerned about him hurting her family.