Carietta "Carrie" White is a 16-year-old girl from Chamberlain, Maine. Her widowed mother Margaret, a fanatical Christian fundamentalist, has a vindictive and unstable personality, and over the years has ruled Carrie harshly with repeated threats of damnation, as well as occasional physical abuse. Carrie does not fare much better at her school where her frumpy looks and lack of friends make her the butt of ridicule.
At the beginning of the novel, Carrie has her first period while showering after a physical education class; she has no understanding of menstruation as her mother never told her about it, believing it to be sin. Her classmates use the event as an opportunity to taunt her; led by Chris Hargensen, they throw tampons and sanitary napkins at her. When gym teacher Miss Desjardin happens upon the scene, she at first berates Carrie for her stupidity but is horrified when she realizes that Carrie has no idea what is happening to her. She helps her clean up and tries to explain. Carrie's mother shows no sympathy for her first encounter with what she calls "the woman's curse".
Miss Desjardin, still incensed over the locker room incident and ashamed at her initial disgust with Carrie, wants all the girls who taunted Carrie suspended and banned from attending the school prom, but the principal instead punishes the girls by giving them several detentions. When Chris, after an altercation with Miss Desjardin, refuses to appear for the detention, she is suspended and barred from the prom and tries to get her father, a prominent local lawyer, to intimidate the school principal into reinstating her privileges.
Carrie gradually discovers her telekinetic powers, which she had apparently possessed since birth, but had not had conscious control over after her infancy, though she remembers several incidents from throughout her life. Carrie practices her powers in secret, developing strength, and also finds that she is somewhat telepathic.
Meanwhile, Sue Snell, another popular girl who had earlier teased Carrie, begins to feel remorseful about her participation in the locker room antics. With the prom fast approaching, Sue convinces her boyfriend, Tommy Ross, one of the most popular boys in the school, to ask Carrie to the prom. Carrie is suspicious but accepts his offer, and makes a red velvet gown. Carrie's mother won't hear of her daughter doing anything so "carnal" as attending a school dance, as she believes that sex in any form is sinful, even after marriage. She also reveals that she knows about Carrie's telekinetic powers, which she considers a form of witchcraft; it seems that they appear every third generation in her family. Carrie, however, is tired of hearing that everything is a sin; she wants a normal life and sees the prom as a new beginning.
The prom initially goes well for Carrie; Tommy's friends are welcoming and Tommy finds himself attracted towards her. Chris Hargensen, still furious, devises her own revenge with her boyfriend Billy Nolan: they fill two buckets full of pig's blood and suspend the buckets over the stage. They rig Carrie's election as prom queen and empty the buckets on Carrie's and Tommy's heads. Tommy is knocked unconscious by one of the buckets and dies within minutes, and he and Carrie are both drenched in blood. Nearly everyone in attendance, even some of the teachers, begin laughing at Carrie, who is finally pushed over the edge. She leaves the building in agonized humiliation, remembers her telekinesis, and decides to use it for vengeance. Initially planning only to lock all the doors and turn on the sprinklers, Carrie remembers the electrical equipment set up for the sound system but turns the sprinklers on anyway. Watching through the windows, she witnesses the deaths of two students and a school official by electrocution, and decides to kill everyone, causing a massive fire that destroys the school and traps almost everyone inside.
Walking home, she burns almost all of Downtown Chamberlain by breaking power lines and exploding gas stations. A side-effect of her telekinesis is "broadcast" telepathy, which causes the city's inhabitants to become aware that the carnage was caused by Carrie White even if they do not know who she is. Carrie returns home to confront her mother, who believes Carrie has been possessed by Satan and that the only way to save her is to kill her. Revealing that Carrie's conception was a result of what may have been marital rape although she admits she enjoyed the sex, she stabs Carrie in the shoulder with a kitchen knife, but Carrie kills her mother by stopping her heart.
Mortally wounded but still alive, Carrie makes her way to a roadhouse where she sees Chris and Billy leaving; after Chris attempts to run her over, she telekinetically takes control of the vehicle and wrecks the car, killing them both. Sue Snell, who has been following Carrie's telepathic "broadcast," finds Carrie collapsed in the parking lot. The two have a brief telepathic conversation. Though Carrie had believed that Sue and Tommy had set her up for the prank, Carrie realizes that Sue is innocent and has never felt real animosity towards her. Carrie forgives her and dies crying out for her mother.
One of the few survivors of the prom is Miss Desjardin, who resigns shortly afterwards, believing that she might have prevented the catastrophe if she had reached out more to Carrie. The principal also resigns. The surviving seniors attend a grim graduation ceremony.
The catastrophe of Chamberlain is regarded in the book as one of the worst disasters in American history, and the survivors of the incident never fully recover from it. Month after month, more and more people start abandoning the town and the few that stay don't have any hopes for the future. It is implied that Chamberlain will eventually become a ghost town. Schools across the nation start to crack down harder on bullying and research into telekinesis is taken more seriously.
Fictional transcripts of Congressional hearings and a final "White Committee" report are shown; at the end, the report concludes that at least there are no others like Carrie so events like these will not happen again. However, the final document in the book is a cheery letter from an Appalachian woman to her sister, talking about her daughter's telekinetic powers and reminiscing about her grandmother, who had similar abilities.