In a dark, seedy club, small-time fighter Rocky Balboa polishes off another nothing boxer, and gets a few dollars in winnings. Stepping out into the night, he walks through mean and broken-down streets, stopping to talk to the couple of people in the neighborhood who know him, including Adrian, his friend Paulie’s overly shy sister, who works in the local pet shop. There, he picks up some pet food, and walks over to his tiny, run-down apartment where only his turtles wait for him.
Daylight brings him to his real job-working as a collector for a hood called Gazzo. Rocky, though, can’t bring himself to break the bones of terrified dock workers, making Gazzo very displeased. Heading over to the gym to work out, Balboa finds that his things have been dumped out of his locker to make room for those of a new fighter. When he goes to yell at the owner-trainer, Mickey, the old man shouts back at him, telling him that he could have been great instead of a mere club boxer and hired hand for a cheap criminal.
Some happiness comes over Rocky’s way when Paulie invites the bruiser over for Thanksgiving dinner with him and Adrian. She and Paulie quickly get into a fight, and the dinner never gets off the ground, but Adrian and Rocky do get the chance to go out on their first date. The fighter’s charm brings her out of her shell, and the two quickly fall in love.
Meanwhile, Apollo Creed, the Heavyweight Champion of the World, has come to Philadelphia for a scheduled match. However, the man he was supposed to fight is unable to be there, and no one else is available. Apollo, however, gets the idea to put on a show that would drive the crowds wild- harp on the idea of America being the land of opportunity by offering a complete unknown the chance to beat him. Thumbing through a book of local fighters, he picks Rocky.
Rocky is called to the gym the following day where Mickey tells him that Creed’s people want to hire him as a sparring partner for the champ. Balboa is eager to take the job, but once he gets to the office, he’s told the truth- that he’s being given the opportunity of a lifetime. With his one chance for recognition and self-respect in front of him, Rocky attends a press conference to tell everyone that he’s accepting.
Rocky begins exercising on his own, and Paulie starts letting him into a meat-packing plant to practice punching against sides of beef. Mickey shows up at Balboa’s apartment and begs him to take him on as a manager-trainer. Rocky can’t believe that after six years of insults, the old man suddenly cares about him, but the boxer feels sorry for him and agrees to hire him. Almost immediately, Mickey puts him through grueling training, determined to bring out the best in Rocky.
The night before the big fight, Apollo is supremely self-confident, convinced that the whole thing will be over in a few rounds. Rocky, on the other hand, has become more introspective and realizes that he probably can’t defeat the champ. However, if he can just go the full fifteen rounds with Creed- something that’s never been done before- he’ll know in his heart that he really is somebody.
As the fight begins, Rocky takes Apollo and everyone else off-guard, smashing away at the champ and racking up points. Creed starts taking the fight more seriously, and the two inflict more and more damage to each other as one round after another passes.
Rocky is slumped on the stool in the far corner of the boxing ring. Mickey works frantically to get Balboa ready for the fifteenth and final round, but Rocky is hurt badly. “I can’t see nothin’,” he says, “You gotta open my eye.”
Mickey winces at the sight. “I can’t.” Rocky pleads with his trainer a second time. “Cut me, Mick, cut me.” Mickey sighs and gives in. A second cornerman slits open Rocky’s swollen eye and drains it of the blood. Rocky lurches back up into the ring and holds his own against an equally battered Apollo. In a near split-decision, Creed is given the final victory and retains the Championship title.
In the mass confusion following the fight, Adrian finally reaches Rocky after having waded through the wild crowds screaming his name. She climbs past Paulie and up into the ring itself, throwing her arms around Rocky’s neck crying: “I love you!” He lovingly hugs and embraces her and declares his own love for her: “I love you!” As they hug each other in a locking grip, they continue declaring their love for each other. As they celebrate their victory in the face of defeat, the final, heart-lifting image freeze-frames on Rocky’s swollen, messy and battered face next to Adrian’s – Rocky Balboa is crowned the true champion in the eyes of the world that night.