In 1985, Ivan Drago (Lundgren), a muscular 6-foot-5, 261-pound Soviet boxer, arrives in the United States with his wife Ludmilla (Nielsen), and a team of trainers from the USSR and Cuba. His manager, Nicolai Koloff (Pataki), takes every opportunity to promote Drago's athleticism as a hallmark of Soviet superiority. Motivated by patriotism and an innate desire to prove himself, Apollo Creed (Weathers) challenges Drago to an exhibition bout. Rocky (Stallone) has reservations, but agrees to train Apollo despite his misgivings about the fight. He asks Apollo whether the fight is against the Russian, or "you against you".
In 2020, human boxers are replaced by robots. Charlie Kenton (Hugh Jackman), a former boxer, owns "Ambush", but loses it in an arranged fight against a bull belonging to promoter and carnival owner, Ricky (Kevin Durand), who sees Charlie as a joke, partially because he beat Charlie up the last time they competed in the ring. Having made a bet that Ambush would win, Charlie now has a debt to Ricky—which he runs out on.
In the four and a half years since winning the world heavyweight title, Rocky Balboa has had a string of successful title defenses (10) and has seen his fame, wealth and celebrity increase. While unveiling a statue of himself at the steps of the Philadelphia Museum of Art, Rocky is publicly challenged by James "Clubber" Lang (Mr. T), a ferocious new boxer rapidly climbing the ranks. Lang accuses Rocky of intentionally accepting challenges from lesser opponents, and after making a sexual remark toward Rocky's wife Adrian (Talia Shire), his challenge is accepted.
Margaret "Maggie" Fitzgerald, a waitress from a Missouri town in the Ozarks, shows up in the Hit Pit, a run-down Los Angeles gym owned and operated by Frankie Dunn, an old, cantankerous boxing trainer. Maggie asks Frankie to train her, but he initially refuses. Maggie works out tirelessly each day in his gym, even after Frankie tells her she's "too old" to begin a boxing career at her age. Eddie "Scrap-Iron" Dupris, Frankie's friend and employee (as well as the film's narrator), encourages and helps her.
Following the fight at the end of Rocky, in which Apollo Creed has successfully defended his heavyweight title in a split decision, he and Rocky are taken to the same hospital. Apollo challenges Rocky to a rematch, but Rocky declines and announces his retirement. His girlfriend Adrian supports this choice, as do his doctors, who reveal he will require surgery for a detached retina, which could lead to permanent blindness. After Rocky is discharged from the hospital, he enjoys the benefits of his life's changes: Rocky's new fame attracts an agent who sees Rocky as a potential endorsement and sponsorship goldmine, and his sudden wealth encourages him to propose to Adrian. She happily accepts, and they marry in a small ceremony. Soon after, Rocky and Adrian happily learn that Adrian is pregnant.
Adonis Johnson Creed grew up without knowing his father Apollo, the one-time world heavyweight champion, and struggles to channel the strength, skill and toughness he inherited from him. After a fight in prison, he receives a visit from Rocky Balboa. Rocky had been given a world title shot by Apollo when he was just a club fighter in Philadelphia (Rocky), had eventually won Apollo's title in a rematch (Rocky II), had befriended him and been coached by him, rediscovering what Apollo called his "eye of the tiger" (Rocky III) and had been in Apollo's corner when Apollo had died in the ring against Ivan Drago (Rocky IV). Rocky shows Adonis who Apollo was and shows he believes Adonis can be a great like his father. Adonis tracks down Rocky at Adrian's Restaurant - the Italian restaurant in Philadelphia that Rocky owns and operates, named after his late wife - and asks Rocky to train him, and although Rocky is reluctant to re-enter the sport of boxing, having already suffered from trauma to the brain (Rocky V) and made a one-off comeback at a very advanced age (Rocky Balboa) before re-entering retirement, Rocky agrees.
In 2006, Rocky Balboa (Sylvester Stallone) has been retired from boxing for twenty years and lives a quiet life as a widower. His wife Adrian Pennino Balboa (Talia Shire) had died from cancer four years earlier. He runs a small but very successful Italian restaurant named after her, where he regales his patrons with stories of his past. He also battles personal demons involving his grief over Adrian's death, the changing times, and his eroding relationship with his son Robert (Milo Ventimiglia), a struggling corporate employee. Paul "Paulie" Pennino (Burt Young), Rocky's brother-in-law and best friend, continues to keep by his side, but is tired of reliving the past.
Shortly after Rocky Balboa's victory over Ivan Drago in Moscow, he, his wife Adrian, his brother-in-law Paulie, and his trainer Tony "Duke" Evers return to the U.S., where they are greeted by Rocky's son Robert. At a press conference, boxing promoter George Washington Duke attempts to goad Rocky into fighting his boxer Union Cane for the World Heavyweight Championship in Tokyo, but Rocky declines the offer. Upon returning home, it is discovered that Paulie unknowingly had Rocky sign a "power of attorney" over to Rocky's accountant, who had squandered all of his money on real estate deals gone sour; in addition, the accountant had failed to pay Rocky's taxes over the past six years, and the mansion is discovered to be unpaid by $400,000.
Rocky "The Italian Stallion" Balboa is a hard-living, but failing prize fighter from an Italian neighborhood of Philadelphia, Pennsylvania. Between fights, he works as an enforcer for loan shark Anthony Gazzo, and is regarded by many of his neighbors as a bum. The World Heavyweight Champion, Apollo Creed, announces plans to hold a match in Philadelphia during the upcoming United States Bicentennial. However, he is informed five weeks from the fight date, that his scheduled opponent, Mac Lee Green, is unable to compete due to an injured hand. With all other potential replacements booked up or otherwise unavailable, Creed decides to spice things up and give a local contender a chance to face him. He settles on Rocky, believing that he will be an easy challenge.
James J. Braddock is an Irish-American boxer from New Jersey, formerly a light heavyweight contender, who is forced to give up boxing after breaking his hand in the ring. This is both a relief and a burden to his wife, Mae; she cannot bring herself to watch the violence of his chosen profession, yet she knows they will have no good income without his boxing.
Corrupt, flamboyant Atlantic City police detective Rick Santoro (Nicolas Cage) attends a boxing match at Gilbert Powell's (John Heard) Atlantic City Arena between heavyweight champion Lincoln Tyler (Stan Shaw) and challenger Jose Pacifico Ruiz. He meets up with his best friend since childhood, Kevin Dunne (Gary Sinise), who is a US Navy Commander working with the Department of Defense to escort Defense Secretary Charles Kirkland (Joel Fabiani) and Powell at the fight after a trip to Norfolk, Virginia. As the first round begins, Dunne is distracted by an attractive redhead named Serena (Jayne Heitmeyer) who wears a ruby ring, and leaves his seat, which is then taken by Julia Costello (Carla Gugino), a mysterious woman with platinum blonde hair and a white satin suit.
Micky Ward (Mark Wahlberg) is an American welterweight boxer from Lowell, Massachusetts. Managed by his mother, Alice Ward (Melissa Leo), and trained by his older half-brother, Dicky Eklund (Christian Bale), Micky has not had a particularly successful career: He's become a "stepping stone" for other boxers to defeat on their way up. Complicating matters, Dicky, a former boxer whose peak of success was going the distance with Sugar Ray Leonard in 1978 (before Leonard became a world champion), has fallen apart since then, becoming addicted to crack cocaine. He is now being filmed for an HBO documentary he believes to be about his "comeback".
Billy Hope (Jake Gyllenhaal) is a boxer who lives in New York City with his wife Maureen (Rachel McAdams) and their daughter Leila (Oona Laurence). During a match in which he defends his World Light Heavyweight title, Billy sustains an eye injury and is convinced by Maureen to retire while he's at the top. At a charity event for the orphanage where he and his wife both grew up, Billy is taunted by an up-and-coming boxer, Miguel "Magic" Escobar, leading to a brawl in which Maureen is accidentally shot and killed by Miguel's brother Hector, who flees.
The film begins with Cassius Clay, Jr. (Will Smith) before his championship debut against then heavyweight champion Sonny Liston. In the pre-fight weigh-in Clay heavily taunts Liston (such as calling Liston a "big ugly bear"). In the fight Clay is able to dominate the early rounds of the match, but halfway through the fight Clay complains of a burning feeling in his eyes (implying that Liston has tried to cheat) and says he is unable to continue. However, his trainer/manager Angelo Dundee (Ron Silver) gets him to keep fighting. Once Clay is able to see again he easily dominates the fight and right before round seven Liston quits, therefore making Cassius Clay the second youngest heavyweight champion at the time after Floyd Patterson. Clay spends valued time with Malcolm X (Peebles) and the two decide to take a trip to Africa.
The film tells the story of middleweight boxer Rubin "Hurricane" Carter, whose conviction for a Paterson, New Jersey triple murder was set aside after he had spent nearly 20 years in prison. Narrating Carter's life, the film concentrates on the period between 1966 and 1985. It describes his fight against the conviction for triple murder and how he copes with nearly twenty years in prison.