Jazz drummer Andrew Neiman attends the prestigious Shaffer Conservatory in New York City, hoping one day to leave a legacy like that of his childhood idol Buddy Rich. Terence Fletcher, the conductor of the Shaffer Conservatory Studio Band, recruits him to play in the Studio ensemble as an alternate for core drummer Carl Tanner. Andrew quickly discovers that Fletcher, although encouraging at first, is relentlessly strict and both verbally and physically abusive towards his students, made apparent when he throws a chair at Andrew, then slaps and berates him for failing to keep tempo during the ensemble's rehearsal of Hank Levy's "Whiplash".
Determined to impress Fletcher, Andrew excessively practices, oftentimes until his hands blister and bleed. After their first set at a jazz competition, Andrew misplaces Tanner's sheet music. Since Tanner cannot play without the sheets, Andrew replaces him for the next set and performs it from memory. After a successful performance of "Whiplash", Fletcher promotes Andrew to core drummer. However, Andrew is taken aback when Fletcher abruptly gives the position to Ryan Connolly, a drummer from a lower-level ensemble within Shaffer. Because of his single-mindedness towards music, Andrew's relationship with his family deteriorates, and he breaks up with his girlfriend, Nicole, to focus on his ambitions. After a grueling five-hour practice session with Tanner and Connolly on "Caravan" during which Fletcher demands they play at the fastest possible tempo, Andrew earns back the core position.
On the way to the next competition, Andrew's bus gets a flat tire. He rents a car but arrives late and forgets his sticks at the rental office. After Fletcher reluctantly agrees to wait, Andrew races back and retrieves them, but is hit by a truck on the way back. He is heavily injured, but crawls from the wreckage and runs to the theater, arriving with a bloodied face and tattered suit just as the ensemble enters the stage. He struggles to play "Caravan", and Fletcher halts the performance to dismiss him from the band. Enraged, Andrew attacks Fletcher onstage but is pulled away by security and expelled from Shaffer.
At his father's request, Andrew meets a lawyer representing the parents of the late Sean Casey, a former student of Fletcher's. Though Fletcher had claimed Casey died in a car accident, in reality he had hanged himself after suffering depression and anxiety allegedly inflicted by Fletcher's abuse. Casey's parents want Fletcher held accountable, and Andrew reluctantly agrees to testify anonymously, leading Shaffer to terminate Fletcher.
Andrew subsequently abandons drumming, but months later encounters Fletcher playing piano at a jazz club. Over a drink, Fletcher admits his teaching methods were harsh but insists they were necessary to motivate his students to become successful, citing an incident in Charlie Parker's rise to fame as an example. He invites Andrew to perform with his band at the JVC Jazz Festival, assuring him that the songs will be the same ones played by the Studio Band; Andrew hesitantly accepts. Andrew calls Nicole to invite her to the performance, but finds out she is in a new relationship.
At JVC, Fletcher confronts Andrew and reveals he knows Andrew testified against him. As revenge, Fletcher leads the band into a song Andrew does not know and was not provided sheet music for. After a disastrous performance, Andrew walks offstage humiliated. His father embraces him backstage, and Andrew returns to the stage, reclaims the drum kit, and cuts off Fletcher's introduction to the next piece by cueing the band into "Caravan". Initially angered, Fletcher resumes conducting. As the piece finishes, Andrew continues into an unexpected extended solo. Impressed, Fletcher nods in approval before cueing the finale.
