The film is about a young girl who raised a genetically modified "super pig" (the titular Okja), and, after she is taken to the United States, goes on a mission to rescue her from mistreatment at the hands of the meat industry.

An international co-production of South Korea and the United States, it stars an ensemble cast headed by child actor Ahn Seo-hyun, along with Byun Hee-bong, Yoon Je-moon, Choi Woo-shik, Tilda Swinton, Paul Dano, Steven Yeun, Lily Collins, Shirley Henderson, Daniel Henshall, Devon Bostick, Giancarlo Esposito, and Jake Gyllenhaal.

In 2017, a young girl named Mija lives in South Korea with her grandfather and their super pig, Okja.

They are visited by Mirando spokesperson and zoologist Dr. Johnny Wilcox, who declares Okja the best super pig, and announces that they will take her to New York City.

He asks another ALF member, K, to translate and tell Mija that they plan to put a recording device in Okja's ear and let her be recaptured by the Mirando Corporation to document how they mistreat animals.

To minimize PR damage to the company, Lucy pays for Mija to come to New York to stage a heart-warming reunion with her pig.

In New York, Mija has to comply with the Mirando Corp. Jay slips into her room and tells her they plan to rescue Okja while on stage.

Lucy surrenders the company to her twin sister Nancy, who contacts a private security firm Black Chalk to take out the ALF members.

Okja is recaptured and the ALF members are arrested, except for Mija and Jay, who are rescued by a remorseful K. Nancy starts full production at the slaughterhouse.

[23] Several independent theatres in South Korea screened the film to much success, with earnings totalling 2.3 billion KRW ($2.1 million USD) from 300,953 tickets sold.

[24] On the film review aggregator website Rotten Tomatoes, the film has an approval rating of 86% based on 241 reviews, with a weighted average of 7.6/10; the site's "critics consensus" reads: "Okja sees Bong Joon-ho continuing to create defiantly eclectic entertainment – and still hitting more than enough of his narrative targets in the midst of a tricky tonal juggling act.

"[25] On Metacritic, the film has a weighted average score of 75 out of 100 based on 36 critics, indicating "generally favorable reviews".