Thirty years after the events of the 1984 All Valley Karate Tournament, Johnny Lawrence's life has taken a rocky turn as he tries to forget a past that constantly haunts him. He seeks redemption by reopening the infamous Cobra Kai karate dojo. But the LaRusso-Lawrence rivalry of yesteryear is reignited when their lives become intertwined with the next generation of "karate kids".
Present day Daniel LaRusso lives a charmed life. That is, until he sees that the Cobra Kai dojo, the source of his teenage angst and rivalry, has been reestablished by Johnny Lawrence. Struggling to launch the business, Johnny starts teaching karate to his teenage neighbor Miguel. Daniel faces his former opponent and old offenses are quickly reignited.
Johnny tries to recruit more students to join the dojo. Troubled by his daughter's friends, Daniel chaperones her high school costume dance. Johnny takes Miguel's training seriously and starts creating a badass.
When Daniel's car dealership billboard is sprayed with lewd graffiti, it consumes Daniel and escalates tensions against a rival. Robby, Johnny's delinquent son, is embarrassed about his father and his new dojo. The bullying escalates against Miguel and motivates Johnny in a surprising way.
Daniel tries to strike a shady deal to undermine Johnny's dojo. Meanwhile, Johnny expands his enrollment ranks in the dojo. Miguel puts his karate practice into reality as Samantha faces rejection in school.
Johnny's dojo class attracts a group of misfits while his son Robby, who harbors ulterior motives, lands a new job. Samantha makes a new friend in science class. Daniel inspires interest in karate from an unlikely person.
Daniel takes on teaching his new pupil using the unconventional techniques from Mr. Miyagi. Robby is tempted to return to his delinquent ways. Johnny helps Miguel with his first date.
Johnny prepares his Cobra Kai students for the next All Valley Karate Tournament and in turn, he is inspired to clean up his life. Daniel is still unaware of his new pupil's background. But as events unfold, it seems nothing has changed between Daniel and Johnny in 30 years.
Despite Johnny's efforts to move forward, he confronts Daniel about the assault on his property. An attempt to appease Johnny makes them revisit the past together. Miguel senses Samantha is lying to him. The dojo students try to intimidate the popular kids at a party.
The highly-anticipated All Valley Karate Tournament brings Johnny and Daniel on opposite sides again, except this time, the new generation of karate students are the combatants. Who will pay the price for ultimate victory?