On-stage, Moretz's work includes her starring role in the original off-Broadway production of The Library (2014) at The Public Theater in New York City.

[12][13] She moved to New York City in 2002, with her mother and brother Trevor, because he had been accepted into the Professional Performing Arts School, which is what first drew her interest in acting.

It was not until her second big-screen acting role, in the 2005 remake of The Amityville Horror, that she earned greater recognition, receiving a Young Artist Award nomination.

Her recurring TV characters include Kiki George in Dirty Sexy Money and Sherri Maltby in Desperate Housewives.

[16] In 2008, Moretz appeared in the Disney animated film Bolt as a younger version of Miley Cyrus' character.

[23] She appeared in the 2012 Tim Burton film Dark Shadows, a remake of the soap opera, playing the role of Carolyn Stoddard,[24][25] a rebellious teenage daughter.

[30] From March 25 through April 27, 2014, Moretz made her Off-Broadway debut in The Library, directed by Steven Soderbergh.

The story follows a 17-year-old classical musician as she deals with the aftermath of a catastrophic car accident involving her family and has an out-of-body experience.

[34] Moretz subsequently starred as Cassie Sullivan in The 5th Wave, an adaptation of the best-selling novel by Rick Yancey.

[35] Hannah Minghella of Sony Pictures said Moretz "embodies the heart, strength and determination that make Cassie such a compelling character.

The ensemble cast includes Asa Butterfield, Anne Hathaway, Daniel Radcliffe and Keanu Reeves.

[40] Also in November, Moretz was announced as the star of Universal Studios' live-action version of Hans Christian Andersen's The Little Mermaid, to be written by Richard Curtis, though she later left the project.

"[49] In 2018, Moretz starred in the drama film The Miseducation of Cameron Post opposite Sasha Lane and Forrest Goodluck revolving around a teenage girl who is sent to a conversion camp.

She signed on for a role in Mattson Tomlin's first film as director, Mother/Android,[64] and featured as the lead in the Amazon Prime Video series The Peripheral based upon the William Gibson novel of the same name.

[65] In 2021, Moretz executive-produced the six-part Snapchat Original series Coming Out highlighting young LGBTQ people.

In an interview with The Advocate, she said, "I hope it is a show that will help to save lives by sharing what coming out means to each individual – that no single 'coming out' story is the same, each one is unique.

[68] In 2012, Moretz also became the face of American youth clothing retailer Aéropostale, appearing at various events, videos and reports.

[70] From 2014 to 2018, Moretz was in a relationship with English model and photographer Brooklyn Beckham, with whom she attended the 2016 Democratic National Convention in support of Hillary Clinton.

[87] In 2016, Moretz voiced her support for Democratic presidential candidate Hillary Clinton on the South Korean show The Brainiacs/Problematic Men.

[88] She also appeared as a speaker at the 2016 Democratic National Convention in July 2016, praising Clinton and encouraging young people to vote.