The film begins in the locker-room fill of teenage girls, including Carrie White (Sissy Spacek). Carrie gets her first period, and after becoming distressed, cries out for help. Instead of helping, the other girls ridicule and harass her, throwing out tampons, sanitary towels and toilet paper to her. Teacher Miss Collins (Betty Buckley) rushes in to stop the commotion. White, who appears to be bottling extreme rage, snaps a light bulb. After questioning Carrie, Miss Collins realizes that Carrie is unaware of the concept of menstruation. Because of this, Miss Collins asks the school principal to excuse Carrie from gym class for a week because of the trauma. Upon her way home, Carrie uses her recently discovered telekinesis to stop a boy from teasing her. While at home, Carrie is tormented by her delusional mother (Piper Laurie), who locks Carrie in a closet and forces her to pray--she believes that Carrie received her period due to sinning.
Miss Collins, still livid about the incident, berates the other girls and forces them through a detention, deliberately physically exhausting them. The leader of the clique, Chris Hargensen (Nancy Allen), refuses to participate, and as punishment, is banned from the upcoming prom. Furious, she blames Carrie for her misfortune. Meanwhile, another one of the girls, Sue Snell (Amy Irving), feels guilty about her part in teasing Carrie, so she asks her boyfriend, Tommy Ross (William Katt), to take Carrie to the prom. Tommy begrudgingly agrees. After Tommy asks her to the prom, Carrie refuses, thinking that yet another trick is being played on her. After a comforting pep talk with Miss Collins, and after Tommy's further insistence, Carrie finally agrees to go to the prom with Tommy.
While everyone else is getting ready for the prom, Chris schemes with her boyfriend Billy Nolan (John Travolta) and best friend Norma (P.J. Soles) to get revenge on Carrie. They go to a farm and slaughter some pigs, drain their blood into a bucket, and place the bucket on one of the rafters in the school gym. Carrie asks her mother's permission to go to the prom. Her mother becomes unhinged at the suggestion, commenting that Tommy is only after her for sex and that this will lead her down a road to perpetual sin. This leads to a violent argument between Carrie and her mother; who uses her telekinesis to slam windows and doors in her home. After another fight between Carrie and her mother the night of the prom, Carrie uses her powers to push her mother into a bed and tells her that she must stop worrying.
Carrie and Tommy arrive at the prom, and Carrie begins to feel accepted by Tommy's peers. Miss Collins relates to Carrie the story of her own prom, telling her she should cherish the memory forever. Carrie and Tommy dance together; Tommy has since fallen for Carrie and kisses her.
As per Chris' instructions, Norma and some of Billy's friends fix the ballots so that Carrie and Tommy are elected prom king and queen. They make their way to the stage, and Carrie finally feels what its like to be accepted.
Meanwhile, Sue sneaks into the prom and sees Chris and Billy under the stage. She realizes their plan: Chris is going to yank a cord and dump the pig's blood all over Carrie as she is declared prom queen. Sue rushes toward the stage frantically, but is intercepted by Miss Collins, who thinks that Sue is out to make trouble for Carrie after seeing that Carrie and Tommy are together. Miss Collins throws her out of the gym, thinking that she was to spoil Carrie's momentum. At that exact moment, Chris yanks the cord, drenching Carrie in pig's blood.
The students gasp and look on in horror. Tommy is furious, but the bucket falls and knocks him unconscious. Carrie snaps and imagines that all of the students and faculty are actually laughing at her, which her mother had warned her would happen. Carrie uses her telekinesis to destroy the gym and kill her peers and teachers, including Miss Collins. As Carrie walks home, a firetruck is seen passing her. Chris and Billy, who safely witnessed Carrie cause the death of the entire student body, attempt to run Carrie over with Billy's car. Carrie uses her telekinesis to destroy the car.
When Carrie returns home, she draws a bath. After she cleaned herself, her mother appears, and tells her she was the result of a strange marital rape. Then, convinced that her daughter is an evil witch, she takes out a chopping knife and stabs Carrie in the back. Carrie falls down the stairs and stumbles away from her mother. When her mother corners her in the kitchen, Carrie uses her power to crucify her mother with kitchen knives & tools. After the death, Carrie becomes wrought with guilt, and using the lit candles, sets her house ablaze. The home eventually collapses and Carrie dies amongst the debris.
Some time later, Sue, having survived the prom night catastrophe, is suffering from depression over the death of her peers. She experiences a nightmare in which she visits the location of Carrie's house. As she reaches down to put flowers on the burnt lot, Carrie's blood-stained hand reaches up from the rubble and grabs her. Sue then wakes up screaming in the arms of her mother.