The movie opens during the collapse of Nazi Germany in the city of Falkenheim, introducing ten-year-old Jojo Betzler, a fervent nationalist eager to serve his country. He has been heavily indoctrinated with Nazi ideals and keeps Adolf Hitler as his imaginary friend. Jojo joins the Deutsches Jungvolk, the junior branch of the Hitler Youth, alongside his best friend, Yorki. Their camp, run by the one-eyed Captain Klenzendorf and his assistant Freddy Finkel, subjects the boys to various training exercises like grenade-throwing and trench-digging.

While Jojo excels in many activities, he struggles with hand-to-hand combat and tries to sneak away. When tasked with killing a rabbit, he hesitates, unable to go through with it. An older boy brutally kills the rabbit instead and mocks Jojo, dubbing him “Jojo Rabbit.” Distressed, Jojo runs into the woods and sits under a tree, sobbing. Soon after, his imaginary friend appears to comfort him, insisting that rabbits are brave for risking their lives for carrots.