SEOUL — “Minari,” the critically acclaimed movie about a hard-luck family of Korean immigrants in the United States, was not exactly a commercial blockbuster in South Korea: Fewer than a million people watched it in 54 days of screening across the country.

But when one of its stars, Yuh-Jung Youn, won the Academy Award for best supporting actress, South Koreans rejoiced not only because it was a first for a Korean actor, but also because of the recipient.

On Monday morning, the South Korean media sent out news flashes when Ms. Youn won her Oscar. Cable channels announced plans to screen her previous films. Social media was abuzz with fans congratulating her.

“Her performance brilliantly helped us relive the memories of our own mothers and grandmothers,” President Moon Jae-in said in a statement, referring to Ms. Youn’s character in the film.

“Woman of Fire,” but left acting to marry Jo Young-nam, one of South Korea’s best-known singers. In the 1970s, she followed him to the United States, where Mr. Jo tried on a career as a gospel singer. The marriage ended in divorce in the 1980s.

“A Good Lawyer’s Wife” (2003), many female actresses declined the role of a woman who has sex with another man while her husband is terminally ill. Ms. Youn took the role, saying she could used the money to redo her living room.

She once performed the role of a spiteful queen in a Korean soap opera so well that people often cursed when they saw her on the street.

“People like her because they know her life story,” said Huh Eun, a retired college media professor in Seoul. “When they think of her, they don’t think of the glorious spotlight usually associated with film stars, but of a woman who has struggled to make a living all these years like the rest of us.”

Ms. Youn’s global breakthrough came when she was offered a role in “Minari.”

quoted Ms. Youn as saying. “This is our first time living this life, so we can’t help but feel regretful and hurt.”

Ms. Youn’s Oscar acceptance speech went viral for a characteristic tongue-in-cheek attitude. The award was presented by Brad Pitt, whose production company financed the film. “Mr. Brad Pitt, finally, nice to meet you!” she said to the American superstar. “Where were you when we were filming in Tulsa?”

“Minari” depicts a Korean family struggling to build a life as farmers in rural Arkansas in the 1980s, when many poor Koreans headed for the United States for a better life. It is the second film about Koreans to make history at the Academy Awards, after “Parasite,” directed by Bong Joon Ho, won four Oscars last year.

“Parasite” grossed more than 10 million viewers within two months of its release. Part of the reason “Minari” failed to achieve the same commercial success in South Korea is because the immigrant experience of the 1980s that it portrays is quickly fading.

These days, far fewer Koreans emigrate to the United States, and those who do are usually the children of rich families who go there to study. That may change, too, as Koreans watch hate crimes involving Asian-American victims soar in the United States.

But Ms. Youn struck a chord with South Koreans in her role as Soonja, the foul-mouthed but loving grandmother in “Minari” who moves from South Korea to the United States to take care of her grandchildren. Her grandson doesn’t consider Soonja a “real grandma” and complains that she “smells like Korea.” They slowly build a bond by playing cards together and sharing Mountain Dew, which Soonja seems to think is a health drink because it is made from “dew from the mountains.”