After a stunning opening credit sequence, Raging Bull opens with Jake LaMotta rehearsing his “act” in the dressing room of a nightclub. He recites Shakespearean monologues and recollects on his boxing career. The rehearsal ends with the repetition of the phrase “That’s entertainment.”
1941. Jake is a svelte, muscular boxer in danger of losing a fight against Jimmy Reeves. At the profane urging of his brother and manager Joey, Jake seems suddenly to wake from a somnambulistic dream state and gives his opponent Jimmy Reeves a pummeling. Unfortunately, it is too little too late as the bell rings and—even though Reeves is physically removed from the ring—Jake suffers his first professional defeat. After returning to New York City, Joey walks down the sidewalk with Salvy Batts, a mafia thug working under Tommy Como, the undisputed mob controller of the boxing industry in New York. Salvy tries once again to convince Joey that Jake can never get a shot at the title without playing ball with Tommy, a situation Jake refuses to consider. Joey lets Salvy know that he already knows this.
Meanwhile, we see Jake revealing that his violent behavior is not restricted to the ring. He gets into a heated argument with his wife over his steak not being cooked to his precise specification. The argument ends with his upending the entire kitchen table. Soon afterward, Joey enters Jake's apartment, and Jake laments over his small hands and complains that his middleweight physique prevents him from fighting heavyweight greats like Joe Louis. Jake then abruptly provokes his brother into hitting him in the face as hard as he can, bare-fisted.
Jake and Joey are at the neighborhood public swimming pool where Salvy and his cohorts hit on a beautiful, young blonde name Vickie. Jake asks Joey if Vickie is in a sexual relationship with anyone, and Joey responds that nobody goes with her because she’s just fifteen. Jake thus sets his sights on the teenager; the very next day, he gets Joey to introduce him to Vickie. Impressed by Jake's convertible, Vickie agrees to go on a date with him. After a game of miniature golf cut short by the disappearance of a ball, Jake takes her to his father's apartment. They soon kiss in front of a photograph of Jake and Joey.
1943. Jake hands future legend Sugar Ray Robinson his first professional loss, thus launching what will become the greatest middleweight rivalry of the 1940s. After the fight, it becomes clear that Jake and Vickie are an official couple. Vickie begins kissing Jake's bruises lingering from the Robinson fight, and Jake becomes sexually aroused. To preserve enough energy for a forthcoming fight (again with Robinson), Jake walks away from Vickie and pours cold water on his erection to suppress his sexual desire. Despite this sacrifice, Jake loses the Robinson rematch three days later, but Jake is nonetheless elevated into the realm of the best of the middleweights. Then, a montage shows a string of Jake's victorious matches and features colored home movie camera footage of Jake's happy domestic life.
1947. Now slightly overweight, Jake is angry with Joey for organizing a fight between him and a young up-and-coming boxer, Tony Janiro. Joey believes Jake can easily win the fight (regardless of his weight), and Vickie agrees with Joey, adding that Janiro is "good-looking and popular," a comment which fuels Jake's ardent sexual jealously and fears about Vickie's infidelity. Realizing that he must commit to a full-time training regimen away from home, Jake asks Joey to keep an eye on Vickie. Joey suggests a night on the town before Jake heads to training camp. Jake, Vickie, and Joey go to the Copacabana nightclub; Tommy and his gang are also there and Salvy invites Vickie over for a drink, which enrages the jealous Jake.
Jake finally agrees to pay his respects to Tommy and proudly predicts that he will destroy Janiro. Shortly thereafter, he makes good on his promise, delivering one of the most vicious beatings to an opponent of his career.
While Jake is away at training camp, Vickie takes advantage of his absence and goes out with Salvy. Joey spots her and starts to drag her out of the club. Salvy asserts that the night-out is innocent, but Joey ambushes him and slams his body with a cab door. The next day, Tommy forces a truce between Joey and Salvy. In a private aside, Tommy makes it clear that no matter how many fights he wins, Jake will never get a shot at the middleweight title if he doesn’t cooperate with the mob. Jake finally agrees to throw his fight—lose purposefully—against the weak-hitting Billy Fox. But Jake's performance is a farce, too obvious; it's clear the fight was rigged. The boxing board suspends Jake for two years because of his participation in the staged bout with Fox.
1949. Banned from the ring for two years, Jake finally gets his shot at the world middleweight championship against current title holder Marcel Cerdan. Before the fight, Tommy offers words of encouragement to Jake, but Jake gets suspicious when he observes Vickie (casually) kissing Tommy and Joey on the lips. Jake beats Cerdan to win the title, but the joy is short-lived.
1950. Jake’s jealousy toward Vickie reaches its peak. Jake confronts Joey about what happened on the night of Joey's fight with Salvy. Enraged and delusional, Jake asks Joey if he's slept with Vickie. Sickened by the question, Joey leaves, and Jake then accuses Vickie of having sex with Joey. He begins to hit her, and in a tumultuous explosion of emotion, Vickie mock-confesses to sleeping with Joey, Salvy, and Tommy. Jake heads back to Joey’s house next door and attacks him. When Vickie shows up and tries to break up the fight, Jake brutally strikes her. The couple eventually reconcile, but Joey and Jake become estranged.
1951. Robinson is destroying Jake in their final bout. Filled with self-hate and masochistic desires, Jake can barely hold himself upright against the ropes, but he nonetheless refuses to plummet to the ground. While Jake previously managed to send Ray down, nobody—not even Robinson—ever managed to get Jake down to the canvas. Jake goads Ray to beat him to a pulp until the referee steps in to end the fight. As he is helped to his own corner, he reminds Robinson that “You never got me down, Ray. You never got me down.”
1956. Retired and grotesquely overweight, Jake and the family live in Florida, and Jake is in the nightclub business. Finally fed up with Jake’s womanizing, Vickie files for divorce and takes the kids with her. Jake, meanwhile, is arrested for allowing underage girls to pimp into his self-named nightclub, though Jake claims to be innocent. On his way down to the lowest point of his life, Jake resorts to prying loose the jewels encrusted in his middleweight boxing championship belt to raise money for his defense, only to be told that the jewels don't have any value without the belt itself. Jake hits rock bottom when he finds himself placed in solitary confinement, howling that he is not an animal as he beats his fist and bangs his head against the cinderblock wall of the cell.
1958. After serving his sentence in prison, Jake is now married to a stripper named Emma and returns to New York City. One night, he sees Joey coming out of a liquor store and attempts to reconcile with him. A reluctant Joey allows Jake to hug him, but reveals no desire to reconnect with the brother who beat him to a pulp over an imagined adulterous affair with Vickie.
1964. The film ends where it began: in the dressing room where Jake rehearses his act. Standing in front of the mirror in all his flabby glory, Jake recites the famous scene from On the Waterfront where Marlon Brando’s character famously insists, "I coulda had class. I coulda been a contender. I coulda been somebody instead of a bum, which is what I am." An off-screen voice informs Jake it’s time to hit the stage and after a quick bit of shadowboxing, he walks out, and the screen goes dark.