Under the tutelage of Rocky Balboa, newly crowned heavyweight champion Adonis Creed faces off against Viktor Drago, the son of Ivan Drago.
Adonis “Donnie” Creed (Michael B. Jordan) has been enjoying success since his loss to Pretty Ricky Conlan, but he faces a new challenge when Viktor Drago (Florian Munteanu), son of the man who killed Apollo, arrives in America to challenge Donnie to a fight. Viktor’s father Ivan (Dolph Lundgren) is more motivated to get back at Rocky Balboa for defeating him in Russia, costing him his respect and marriage. Rocky (Sylvester Stallone) refuses to train Donnie for the fight, fearing that he may succumb to the same fate as his father. To make matter more complicated, Donnie becomes engaged to Bianca (Tessa Thompson), and she becomes pregnant with his child.
Donnie faces Viktor, but ends up seriously injured when Viktor cracks his ribs and knocks him out cold. Viktor gets disqualified when he knocks Donnie out while he is down, but Donnie is left damanged physically and emotionally.
Mary Anne Creed gets in touch with Rocky and convinces him that Donnie needs his help. Bianca gives birth to a baby girl named Amara, but sadly, she turns out to be born deaf. Rocky then starts to train Donnie for the rematch.
Donnie goes for round two with Viktor in Moscow. Viktor’s mother and Ivan’s ex-wife Ludmilla is in attendance, while Rocky, Bianca, and Mary Anne are there for Donnie. Although Viktor is winning at first, Donnie remains strong and never stays down, eventually getting in some good hits. When it looks like Donnie will win, Ludmilla abandons her son again, which removes his will to win. Ivan eventually throws in the towel, and Donnie remains the champion.
Rocky travels to Chicago to visit his son and meet his grandson, while Donnie brings Bianca and Amara to Apollo’s grave.
Kiev, Ukraine – Ivan Drago (Dolph Lundgren) wakes up his son Viktor (Florian Munteanu) to start training. They later go to a boxing match where Viktor competes against another man. With his massive size and strength, Viktor knocks out his opponent. Watching them is a promoter named Buddy Marcelle (Russell Hornsby).
In the three years since he made a name for himself, Adonis “Donnie” Creed (Michael B. Jordan) has managed to score seven wins after losing to Pretty Ricky Conlan. He is set to go up against Danny “Stuntman” Wheeler (Andre Ward). Donnie is visited by his girlfriend Bianca (Tessa Thompson) just before the match. Donnie steps into the ring and fights Wheeler, eventually winning and earning the cheers of thousands of fans.
After the match, Donnie approaches Rocky Balboa (Sylvester Stallone) with an engagement ring that he wants to give to Bianca, but he isn’t quite sure what to say. He asks Rocky what he said to Adrian when he proposed, and Rocky says it was something stupid, but it was his way of saying how much he loved and needed her. He tells Donnie to let his heart do the talking. That night, Donnie tries to propose to Bianca after she gets out of the shower, and he expresses his feelings toward her, but her hearing aid wasn’t properly tuned, so she didn’t hear anything and just sees Donnie on one knee with the ring. Bianca is overwhelmed initially and isn’t sure what to think, but after Donnie assures her how much she means to him, she accepts his proposal.
Rocky visits Adrian’s grave to talk to her. He mentions that he hasn’t spoken to their son Robert since he left Philadelphia, and he hasn’t even met his grandson.
The Dragos arrive in Philly with Buddy backing them. Ivan visits Rocky’s restaurant to face his nemesis for the first time in over 30 years. Meanwhile, Donnie and Bianca go out as they watch a news report on Viktor having challenged Donnie to fight. The newspeople don’t fail to mention why this match is one to watch, being that Viktor is the son of the man who killed Donnie’s father. Ivan tells Rocky just how much he lost when Rocky defeated him back then. He lost all respect from Russia, and his wife left him and Viktor, so this match is especially personal to Ivan.
During one of Bianca’s concerts, Buddy approaches Donnie to essentially goad him into fighting Viktor. Afterwards, Donnie goes to talk to Rocky about the match. Because of what happened to Apollo when he fought Ivan, Rocky doesn’t want to see history repeat itself. He tries to convince Donnie to rethink his decision to fight Viktor, but Donnie is adamant in going along with it. Rocky decides to sit this one out and refuses to train Donnie for this fight.
Donnie and Bianca, now settling in a new apartment in Los Angeles, later go to the home of Mary Anne (Phylicia Rashad) to try and tell her about the fight. When Donnie tries to approach the subject, Mary Anne instinctively guesses that Bianca is pregnant. Although the couple laughs it off, Bianca then goes to take a pregnancy test, which confirms that she is. Donnie then goes to tell Mary Anne about the fight. She is obviously not thrilled to hear that Donnie wants to fight, nor does she want to hear him involve her or Apollo in his reasoning for going through with it.
Donnie goes to find Tony “Little Duke” Evers (Wood Harris), son of the man who trained Apollo. He asks Little Duke to train him for the upcoming match.
Soon, a match between Donnie and Viktor is held. Prior to the match, Ivan makes a comment about Apollo that almost sends Donnie into a rage. During the match, Donnie seems confident in himself, managing to get in a few good head shots to Viktor, but Viktor comes back with some powerful shots of his own. Rocky watches the fight from his restaurant. Viktor delivers some hard punches to Donnie’s ribs, eventually fracturing them. He lands one more brutal rib shot, which takes Donnie down, but Viktor goes for an illegal head shot that knocks Donnie out. Viktor is disqualified for this move, while everyone else watches with concern as Donnie is out cold.
Donnie spends time recovering, but his spirit and drive is broken. He starts to become distant from Bianca. Little Duke later approaches Donnie and tells him Viktor wants a rematch since Donnie still holds the championship title, and he has to pick an opponent to fight soon, or else he will forfeit the title. Donnie just appears disinterested. To help him out, Mary Anne sends a message to Rocky telling him Donnie needs him, written on the back of a sonogram picture of Donnie and Bianca’s baby. Rocky makes a surprise appearance at Donnie’s apartment to inspire confidence in him.
The Dragos have a celebratory dinner for Viktor’s success, which is disrupted when Ivan’s ex-wife and Viktor’s mother Ludmilla (Brigitte Nielsen) shows up with her new husband out of the blue. Viktor is displeased and walks out, but Ivan follows him and insists that these people are there for them.
Eventually, Bianca gives birth to a baby girl that she and Donnie name Amara. The doctors then do a test on Amara to see if she has the same hearing problem as her mother. To their dismay, the doctors determine that Amara is born deaf. Outside, Rocky makes an attempt to call Robert, but he backs down.
Rocky decides to start training Donnie for the rematch by bringing him to a desert location to reinvigorate his spirit. Meanwhile, Ivan puts Viktor through a more intense and harsh training session.
The night of the rematch comes and takes place in Moscow. The crowd of Russians boo as Donnie comes in, but Rocky, Bianca, and Mary Anne are there to support him. As the match begins, Viktor takes the lead with several shots to Donnie, including back at his ribs. Viktor wins the first couple of rounds, but Donnie perseveres and never stays down. Rocky tries to give Donnie a method of taking Viktor down, while Ivan tells Viktor to break Donnie again. Soon, Donnie starts to land more effective blows, even managing to take Viktor down at least twice. When it appears that Donnie is winning, Ludmilla leaves with her husband. Ivan and Viktor take notice, and Viktor appears to just lose the will to win. Donnie starts laying in more hits, until Ivan, who can no longer bear to watch, throws in the towel, thereby conceding the fight and allowing Donnie to remain victorious. Ivan goes to his son, who brushes off his father, thinking he will only give him hell for the loss, but Ivan instead embraces Viktor.
Rocky finally travels to Chicago to visit Robert (Milo Ventimiglia) and he meets Robert’s son Logan (Robbie Johns). Robert introduces Logan to his grandfather and invites him inside. Rocky gives his son a hug.
Donnie goes with Bianca to visit Apollo’s grave. He makes peace with his father’s name and legacy, now that he is in the process of shaping his own. He then introduces Amara to her grandfather.