In 2007, Lucy Mirando, portrayed by Tilda Swinton, ascends to the role of CEO of the Mirando Corporation, following in the footsteps of her controversial grandfather, father, and ruthless twin sister, Nancy. She makes a groundbreaking announcement about the breeding of a remarkable type of super pig, with plans to distribute twenty-six of these exceptional animals across the globe. A decade later, the finest among them will be declared the winner.
Fast forward to 2017, we meet a spirited young girl, Mija, brought to life by Seo-Hyeon Ahn, who cherishes a simple life in the serene countryside of South Korea alongside her grandfather and her beloved super pig, Okja. Their lives take a dramatic turn when Jake Gyllenhaal, embodying the charismatic Mirando spokesperson and zoologist Dr. Johnny Wilcox, visits their home and proclaims Okja as the prime super pig. Mija's grandfather explains to her the sacrifice he made—a gold pig symbolizes his savings since they were prohibited from purchasing Okja directly. Heartbroken, Mija resolves to find Okja after witnessing her being loaded onto a truck.
In her quest, she chases the vehicle but soon finds herself in the middle of a confrontation, instigated by the Animal Liberation Front (ALF). Amidst the chaos, Mija and Okja escape, and the ALF rescues them. The leader of ALF, Jay, reveals shocking truths about Okja's origins—she is a genetically modified creature, the product of Mirando's unethical experiments. The corporation plans to reintroduce these super pigs into the food chain, concealing their cruel practices. They propose a plan to use Okja as a means to expose Mirando's inhumane treatment of animals to the world by implanting a recording device in her ear.
Despite her pleas to return to the mountains, Mija is misled into believing that the ALF's intentions align with her own. They ultimately abandon her, leading to Okja's recapture. Meanwhile, footage of their escapade circulates widely, prompting Lucy to bring Mija to New York for a staged reunion with Okja. However, tragedy strikes when Okja is taken to a lab for forced breeding, suffering unspeakable horrors. As Paul Dano, playing the committed Jay, vows to save them both, Mija navigates the city learning English while trying to maneuver through the Mirando Corporation's demanding agenda.
A chaotic parade to promote Mirando’s agenda unfolds in the city, where Mija eventually encounters a distressed Okja, who, mistaking her for a threat, reacts aggressively. In a heart-wrenching moment, Mija calms Okja, rekindling their bond just as a video exposing the corporation's abuses is leaked, causing public outcry against both Lucy and the company. Amidst the turmoil, Nancy seizes control of the corporation, leading to the capture of ALF members and Okja.
In a desperate bid to rescue Okja from a slaughterhouse, Mija witnesses the harrowing fate of many super pigs. She sees Okja at the brink of death and desperately tries to negotiate for her life, offering her golden pig as a trade, prompting an emotional reaction from a Mirando employee—only for Nancy to arrive and insist on the slaughter. With resolve, Mija escapes with Okja and a new piglet, returning to her grandfather's home.
In a poignant post-credits scene, Jay is released from prison, joining his ALF companions as they prepare for a significant meeting that could change the fate of Mirando shareholders forever.
