Moretz moved from Georgia to New York in 2001 with her mother and her older brother Trevor because he was accepted into a professional performing arts school; this initially got her interested in acting. Her Hollywood career began when she and the rest of her family moved to Los Angeles in 2003. Her first role in Hollywood was as Violet in two episodes of the series The Guardian, and her first film role was as Molly in Heart of the Beholder.
It was not until her second big-screen acting role in the remake of The Amityville Horror (2005) that Moretz earned greater recognition in the form of a Young Artist Award nomination. After Amityville, Moretz's acting career progressed further when she received several guest-starring roles on TV, as well as a role as one of the family children in Big Momma's House 2. Among the most notable of her TV roles are Candy Stoker in an episode of My Name Is Earl and Sherri Maltby in Desperate Housewives. Moretz also voiced the U.S. version of Darby in My Friends Tigger & Pooh.
In 2010, Moretz appeared as Hit-Girl in director Matthew Vaughn's superhero film Kick-Ass, based on the graphic novel of the same name by Mark Millar and John Romita, Jr., for which she has received widespread critical acclaim. Moretz trained with Jackie Chan and his stunt crew for three months prior to filming Kick-Ass and did most of her own stunts while filming on location. Also that year, she played Abby, a 12-year-old vampire, in Let Me In, the American Remake of the Swedish film Let the Right One In, which was released in 2010. On that year, Moretz was cast as Little Anne Sliger in the psychological thriller Texas Killing Fields.
Moretz's projects for 2011 included Hugo and Hick. She also portrayed Carolyn Stoddard in Tim Burton's film adaptation of 1960s Gothic soap opera Dark Shadows, released in 2012. In 2013, she reprised her Star-Making Role as Hit-Girl in Kick-Ass 2 and starred in the re-adaptation of Stephen King's classic Carrie. In 2014 her films included The Equalizer, the reboot of the cult TV series, and the film adaptation of If I Stay.
Moretz has been in and on again off again relationship with Brooklyn Beckham (son of Victoria Beckham) for several years.
In mid 2016 she announced she would be taking a hiatus from acting, and would be dropping out of all her current projects - including the live action remake of The Little Mermaid. Moretz explained it as "Its not particularly time off, Im just becoming more picky and particular about what roles Im choosing. I think as an actor you have a huge opportunity to find yourself through the roles that you choose. I think its my time, right now in my life, to figure out who I am and what I am and what I want and what this industry means. Why not sit back, slow down, realize Im 19 and go, Hey, lets make stuff that really, really hits hard with who I am and helps me figure out what it means to be a 19-year-old actor who is just doing her thing.' I pulled the plug on all my movies because I want to reassess who I am and find myself within my roles again. Im realizing that I can slow down."
- The Guardian as Violet
- Heart of the Beholder as Molly
- The Amityville Horror (2005) as Chelsea
- My Name Is Earl as Candy Stoker
- Big Mommas House 2 as Carrie
- Desperate Housewives as Sherry Maltby
- The Poker House as Cammie
- Dirty Sexy Money as Kiki George
- My Friends Tigger and Pooh as Darby
- Bolt as Young Penny
- 500 Days of Summer as Rachel
- Diary of a Wimpy Kid as Angie
- Kick-Ass as Mindy "Hit-Girl" Macready
- Let Me In as Abby
- 30 Rock as Kaylee Hooper
- Hugo as Isabelle
- Texas Killing Fields as Anne Sliger
- Hick as Luli McMullen
- Dark Shadows as Carolyn Stoddard
- Carrie (2013 remake) as Carrie White
- Kick-Ass 2 as Mindy "Hit-Girl" Macready
- Dishonored as Lady Emily
- Laggies as Annika
- The Equalizer as Teri
- Dark Places as Diondra
- Clouds of Sils Maria as Jo-Anne Ellis
- If I Stay as Mia
- The Fifth Wave as Cassie Sullivan
- Suspiria (2018) as Patricia Hingle
- The Miseducation Of Cameron Post as Cameron Post
Chloë Moritz and her works provide examples of:
- Action Girl: As Hit-Girl in Kick-Ass, Cassie in The Fifth Wave.
- Adventures in Comaland: The premise of If I Stay, in which her character is rendered comatose by a car accident.
- Badass Adorable: Particularly as her Star-Making Role as Hit-Girl in Kick-Ass.
- Creepy Child / Stringy-Haired Ghost Girl: Enid in the Funny or Die sketch video "Scary Girl." Also her roles in Let Me In and Carrie.
- Dark and Troubled Past: She professes to intentionally seek out roles that are drastically different from her true self for the challenge.
- In The Poker House, she is the youngest daughter of a drug-addicted prostitute with a violent pimp.
- In Kick-Ass, she's deprived of any real childhood and is instead trained from age five by her father to be a vigilante assassin.
- In Let Me In, she is a two-century-old vampire masquerading as a 12-year-old girl who lives with a caretaker who commits serial murder to keep a fresh supply of blood to feed her.
- In Texas Killing Fields, the first thing we learn about her character is that she's on juvenile probation for reasons that aren't made clear. She is later kidnapped by her own older brother and his friend with the intent of murdering her before she's rescued by a hero cop.
- In Hick, she runs away from her neglectful mother and alcoholic father to hitchhike to Las Vegas. Along the way, she tries cocaine, helps rob a convenient store and possibly gets raped by her psychotic companion (and nearly raped a second time), then shoots and kills said companion.
- In Carrie, she plays the main character, and...well, you know the story.
- In The Equalizer, she plays a 16-year-old prostitute.
- In The Miseducation of Cameron Post, she plays a lesbian teen being sent to a straight conversion camp after being outed.
- Deadpan Snarker:
- On Jimmy Kimmel Live! as part of his Mean Tweets feature:Moretz: "Chloe Moretz or whatever her stupid name is looks like my asshole. Seriously, there is nothing attractive about her whatsoever." [beat] You must have a really bleached asshole.
- Weaponised, with devastating effect, on the BBC Radio 1 spot ''Playground Insults'', in which she went toe-to-toe against Seth Rogen to see which could deliver the other the most devastating childish insult. Worth it just for the extraordinary snarly expression that she adopts in an attempt to stop herself laughing.Rogen: You have dick rings on your pants. Four little dick rings on each pant leg. One...two...in Europe these are known as "Prince Albert". [Moretz shuts her eyes and covers her mouth to stop from cracking up] So you have a total of eight Prince Alberts, just danglin' off your leg. There's eight Prince Albert-less dongs out there...just lookin' for their rings.
Moretz: They couldn't even pierce yours. It's so small. [Rogen starts to crack up. Moretz cracks up too] ...Yep. We got there. We're there.
- On Jimmy Kimmel Live! as part of his Mean Tweets feature:
- Little Miss Badass: Her portrayal of Hit-Girl in Kick-Ass might be the ultimate embodiment of this.
- Parental Abandonment: In virtually every single major role she's had, one or both of her character's biological parents are out of the picture by the middle of the film if not from the start.
- Sitcom Arch-Nemesis: Her as Kaylee Hooper, to Jack Donaghy in 30 Rock.
- Troubling Unchildlike Behavior:
- Her characters in Kick-Ass, Let Me In, Hick and The Equalizer.
- Played for Laughs to some degree in 30 Rock, where Kaylee Hooper is a match for Jack Donaghy in sheer ruthlessness...but her motivations are age-appropriate. For instance, she gets the contestants on America's Kidz Got Singing drunk in order to get herself expelled from her school in Philly so her grandpa would send her to a more prestigious boarding school in New York—and incidentally, her boyfriend is a freshman at NYU.
- Wise Beyond Her Years: Many of her characters; she even seems to be this in real life.
- Younger Than They Look: The fact that she can pass for five years older than she is helps pull off the trope listed above.