Cyrus, leader of the Gramercy Riffs, the most powerful gang in New York City, calls a midnight summit of all the city’s gangs, requesting them to send nine unarmed delegates to Van Cortlandt Park. The Warriors, from Coney Island, attend the summit. Cyrus proposes to the assembled crowd a permanent citywide truce and alliance that would allow the gangs to control the city since they outnumber the police by three to one.
Most of the gangs applaud his idea, but hidden in the crowd, the Rogues leader Luther shoots Cyrus dead just as the police arrive and raid the summit. In the resulting chaos, Luther frames the Warriors’ leader Cleon for the murder, and Cleon is beaten down and apparently killed by the Riffs. Meanwhile, the other Warriors escape, unaware that they have been implicated in Cyrus’ murder. The Riffs put out a hit on the Warriors through a radio DJ. The Warriors’ “War Chief” Swan takes charge of the group as they try to make it back home.
The Turnbull ACs spot the Warriors and try to run them down with a bus, but the Warriors escape and board an elevated train, taking advantage of an unstated protocol among the gangs that forbids them from fighting one another in the subways. On the ride to Coney Island, the train is stopped by a building fire alongside the tracks, stranding the Warriors in Tremont, in the Bronx.
Setting out on foot, they come across a lower-echelon group named the Orphans who were not invited to Cyrus’ meeting and who are sensitive and belligerent about their low status in the city’s gang hierarchy. Swan makes peace with the Orphans’ leader, Sully, who agrees to let the Warriors pass through their territory unharmed. However, a young woman named Mercy mocks Sully as a “chicken” and instigates a confrontation.
Goaded by Mercy, Sully insists that the Warriors must remove their gang clothing before he will let them pass. The Warriors refuse, prompting the Orphans to challenge them to a fight. Outnumbered and unarmed, Swan and the Warriors throw a Molotov cocktail at a car, blowing it up and using the opportunity to escape to the subway station. Impressed, and desperate to escape her depressed neighborhood, Mercy follows the Warriors.
When they arrive at the 96th Street and Broadway station in Manhattan, they are chased by police and separated. Three of them, Vermin, Cochise, and Rembrandt, board a train to Union Square, while Fox, struggling with a police officer, falls onto the tracks and is run over by a train as Mercy escapes.
Swan and the remaining three Warriors – Ajax, Snow, and Cowboy – are chased by the Baseball Furies into Riverside Park, where a brawl ensues in which the Warriors manage to outwit and defeat the swarm of attackers. After the fight, Ajax notices a lone woman named Chloe in the park, and insists on lagging behind to chat her up. He becomes sexually aggressive and is arrested when Chloe turns out to be an undercover police officer.
Arriving at Union Square, Vermin, Cochise, and Rembrandt are seduced by an all-female gang called the Lizzies and invited into their hideout. The trio manages to escape the Lizzies’ subsequent attack, learning in the process that everyone believes they murdered Cyrus.
Having scouted ahead on his own, Swan returns to the 96th Street station and finds Mercy there. A police officer corners them, but Swan throws a baseball bat and immobilizes him; when backup officers arrive, Swan and Mercy flee into the tunnel. The sexual tension between the two boils over into an argument, which ends with Swan spurning Mercy and continuing on to Union Square, where he reunites with the other Warriors. They get into a fight with the roller-skating, overall-clad Punks and win, and Mercy proves that she can hold her own in combat. Meanwhile, a member of a different gang visits the Riffs and tells then that he saw Luther shoot Cyrus.
The Warriors finally arrive at Coney Island at dawn, only to find Luther and the Rogues waiting for them. When asked, Luther tells Swan he shot Cyrus for no reason, only for the thrill of it. Swan challenges Luther to a one-on-one fight, but Luther pulls a gun instead. Swan dodges his shot and throws a knife into Luther’s forearm, disarming him. The Riffs arrive and apprehend the Rogues, taking a moment to acknowledge the Warriors’ courage and skill. Luther screams in anguish as the Riffs descend upon him and the other Rogues, while the Warriors depart the scene.
The radio DJ announces that the big alert has been called off and salutes the Warriors with a song, “In the City”. Swan, Mercy, and the rest of the gang walk down the beach, illuminated by the rising sun.