The film swept top categories that also included the international feature, best director and original screenplay trophies.
Director Bong Joon Ho's film "Parasite", a twisted satire on class divide, leap-frogged through 92 years of Oscars history to become the first non-English and South Korean film ever to win the best picture award.
The movie, a cleverly crafted, stylish genre-bending story broke the "one-inch long subtitle barrier" that its director Bong famously had talked about in the run-up to the Oscars, swept the top categories that also included the international feature, best director and original screenplay trophies.
The director, who had already come up the stage thrice and promised to drink away the night, let his producers bask in the limelight for the big finish.
"I'm speechless. We never imagined this to ever happen. We are so happy. I feel like a very opportune moment in history is happening right now," co-producer Kwak Sin Ae said in her acceptance speech via interpreter Sharon Choi.
While "Parasite's" chances in the international category were a lock, the best picture and director win is a huge upset for British filmmaker Sam Mendes' war drama "1917".
The South Korean film, about a poor family which worms its way through a rich and gullible household to tragi-comic results, was also up against seven other films: “Ford V. Ferrari,” “The Irishman,” “Jojo Rabbit," “Joker,” “Little Women,” “Marriage Story” and “Once Upon a Time in Hollywood".
"Parasite" has been on an unstoppable march since its debut at the Cannes Film Festival where it became the first South Korean film to win the top, Palme d'Or, award.
The universal love and acclaim that the film has been receiving warmed the hearts of even the notoriously conservative Academy voters, leading up to a historic night that will pave the way for other international films.
Joaquin Phoenix took home the prize of Best Actor for his portrayal of Arthur Fleck in 'Joker' and became the second actor, after late Heath Ledger, to win an Oscar for playing the character.
This is the second time two actors have won Oscars for playing the same character. In 1972, Marlon Brando won the best actor Oscar for playing Vito Corleone. Two years later, Robert De Niro won the best supporting actor for playing a younger version of the character.
Renee Zellweger's poignant portrayal of yesteryear actor-singer Judy Garland helped the actor win the best actress at the 92 Academy Awards here.
"Miss Garland you are certainly among the heroes who unite and define us and this is certainly for you," Zellweger said.
The 50-year-old actor led the award season right from the start with 'Judy' and she was a frontrunner in the category despite competition from stars such as Charlize Theron (“Bombshell”) and Scarlett Johansson (“Marriage Story”).
(With agency inputs)