Carrie White (Chloë Grace Moretz) is a girl in her last three months of her senior year at Ewen High School in Maine. One day, while showering after gym class, Carrie has her very first menstrual period. Knowing nothing of menstruation, she thinks she's bleeding to death. The other girls laugh at Carrie and tease her by throwing tampons and feminine napkins at her. One of the girls, Chris Hargensen (Portia Doubleday), who has long bullied Carrie, records the event on her smartphone and later uploads it to YouTube. The gym teacher, Rita Desjardin (Judy Greer), comforts Carrie and takes her to the office. Carrie's deeply religious mother, Margaret (Julianne Moore), is called and picks Carrie up from school early. Believing Carrie's period to be a "sin", Margaret locks Carrie into a "prayer closet". As Carrie screams to be let out, she makes a crack on the door. Both Margaret and Carrie are surprised at this, and Carrie realizes she has telekinetic powers.
The next day, Miss Desjardin informs the girls who teased Carrie that they will have detention for the rest of the week with her. When Chris tells her she won't go, Miss Desjardin informs her that anyone who doesn't show up for detention will be suspended for three days and banned from the prom. Chris, feeling that she did nothing wrong, tries to encourage her friends not to appear at detention, and when her friends refuse, Chris vows revenge. When Chris' lawyer father threatens to sue the school unless Chris' suspension is rescinded, Miss Desjardin reveals that someone uploaded a video of the shower incident to YouTube, most likely Chris. Chris' father urges his daughter to hand over her phone to prove her innocence, but Chris storms out of the office.
Carrie researches telekinesis and learns how to harness her abilities. Sue Snell (Gabriella Wilde), one of the popular girls that took part in teasing Carrie in the shower room, feels bad about what she did and tries to find a way to make it up to her. Sue asks her athlete boyfriend Tommy Ross (Ansel Elgort) to take Carrie to the prom and show her a good time. When Tommy asks Carrie, she is at first suspicious, but then accepts Tommy's invitation. Carrie informs her mother that she has been invited to the prom, but Margaret refuses to permit Carrie to attend it. In pleading her mother for permission, Carrie manifests her telekinesis, which Margaret believes come from the Devil. Carrie explains she is not the only one who harbors telekinetic abilities, but Margaret is unmoved, believing that Carrie has been corrupted by sin.
Chris, her boyfriend Billy Nolan (Alex Russell), and several of his friends slip onto a nearby farm, where they kill a pig and drain its blood into a bucket. Chris and Billy then break into the gym and hoist the bucket to the ceiling. On the night of the prom, Margaret tries to prevent Carrie from going to the prom, but Carrie telekinetically locks her mother in the prayer closet. When she arrives at the prom, Carrie seems to enjoy herself. To the surprise of everyone, Carrie and Tommy are named prom queen and king. This is revealed to be the result of Chris' best friend Tina (Zoë Belkin) slipping fake ballots into the ballot box as part of Chris and Billy's plan. Meanwhile, Sue, who is at home, receives a text from Chris taunting her about her plan of revenge on Carrie. Sue drives to the prom, arriving just as Carrie and Tommy are about to be crowned. Miss Desjardin spots Sue and hustles her out, suspecting Sue is planning to humiliate Carrie.
Chris dumps the bucket of pig's blood onto Carrie and Tommy, drenching them. The bucket falls onto Tommy's head, knocking him unconscious. The video that Chris filmed of her in the shower then appears on large screens above the stage. An enraged Carrie uses her telekinesis to knock everyone to the ground, and after locking all the doors to prevent anyone from escaping (and preventing Sue from entering), begins sending objects flying throughout the gym, killing people. Miss Desjardin and a few students are able to escape. As the school burns to the ground, Carrie leaves the gym covered in blood, leaving a trail of fire and mass destruction in her wake. When Chris and Billy attempt to flee in Billy's car, Carrie causes the road in front of them to cave in, forcing them to turn around. Seeing Carrie before them, Chris urges Billy to run Carrie over, but Carrie brings the car to a sudden stop, severely injuring Billy, and then throws the car into a gas station, killing Chris, before the car explodes.
When Carrie gets home, and sees that the closet in which she locked her mother has been torn open. After Carrie washes off the blood, she sees Margaret and they embrace. Margaret tells Carrie about the night of her conception, relating that after having shared a bed platonically for some time, they felt temptation one night, and after praying for strength, Carrie's father "took" Margaret, who found that she enjoyed the experience. Margaret pulls out a knife and stabs Carrie in the back. Carrie flees, and after Margaret slashes her several more times, Carrie uses her telekinetic powers to levitate a large number of knives, impaling Margaret repeatedly, and pinning her against a wall in the pose of a crucified person. Carrie then releases her mother and cradles her as she dies in her arms. Realizing what she has done, Carrie becomes hysterical and makes stones start to rain from the sky to crush the house, until Sue shows up. A furious Carrie grabs Sue with her powers, but is surprised to sense something within Sue, and tells her that her baby is a daughter. Sue, who is shocked to learn that she is pregnant, is then moved outside of the house by Carrie and gently placed on the ground. The house collapses down and apparently kills Carrie.
During a voice-over of her testimony in court regarding in the incident at the prom, in which most of her friends, including Tommy, were killed, Sue visits Carrie's grave and places a single white rose by the headstone, which has been vandalized with the words "Carrie White Burns In Hell". A series of cracks then splinter the gravestone's surface.