Director Paul Thomas Anderson personally won three Oscars, the first of his career, for his political thriller that tackles the hot-button issues of immigration raids and white supremacy.

"You make a guy work really hard for one of these," he said to laughter as he accepted the award for best director.

"I wrote this movie for my kids to say sorry for the housekeeping mess that we left in this world we're handing off to them," he said after collecting the best adapted screenplay prize.

"But also with the encouragement that they will be the generation that hopefully brings us some common sense and decency

One Battle tells the story of a pot-addled ex-revolutionary, played by Leonardo DiCaprio, who struggles to remember passphrases in a battle of wits against the terrifying Colonel Lockjaw, played by best supporting actor winner Sean Penn.

The film also won best editing and the inaugural award for casting.

Anderson is one of the greatest auteurs of contemporary US cinema, but until Sunday had never won an Oscar, despite 11 previous nominations for acclaimed films including There Will Be Blood and Boogie Nights.

Ryan Coogler's Sinners, a bluesy vampire fable that offers a meditation on America's difficult racial history, had come into the evening with a record-tying 16 nominations.

It left with four awards, including best original screenplay for Coogler and best actor for Michael B. Jordan, who plays gangster twin brothers Smoke and Stack seeking their fortune in the segregated South.

Jordan told reporters backstage that he had created detailed journals to flesh out the backstories of both roles in order to clearly express "those nuances between the two."

Other prizes were best score for Ludwig Goransson and best cinematography for Autumn Durald Arkapaw, the first time a woman won in that category.

Coogler called his writing award "an incredible honor" and told journalists he credited a creative writing professor for his success.

Both One Battle and Sinners were produced by Warner Bros. Studio, which was the subject of an intense bidding war between Paramount and Netflix.

The studio claimed 12 of the 24 awards on offer on Sunday.

In perhaps the least surprising award of the evening, Jessie Buckley won best actress for her portrayal of William Shakespeare's heartbroken wife Agnes navigating the loss of their son in Hamnet.

Buckley told journalists backstage that it felt "crazy" to win the award on what is Mother's Day back in her native Ireland.

"I feel like what a gift to get to explore motherhood through this incredible mother that Agnes is," she said.

Amy Madigan took home the Oscar for best supporting actress for her turn as a demented witch in horror film Weapons.

The veteran performer, who scooped the Actors Award two weeks ago, said: "I was in the shower last night, and I thought, 'Well, this must be a special day, because I'm shaving my legs'."

Norwegian family drama Sentimental Value was named best international feature.

KPop Demon Hunters won for best animated feature and best original song for "Golden."

Veteran host Conan O'Brien kept proceedings light and funny, with his signature blend of zany satire.

That included a swipe at allies of President Donald Trump, who had so objected to Puerto Rican artist Bad Bunny being the star of the Super Bowl halftime show that they had put on their own.

"I should warn you tonight could get political, okay?" he told Tinseltown's biggest names.

"And if that makes you uncomfortable, there's an alternate Oscars being hosted by Kid Rock."

A lengthy In Memoriam segment paid emotional tribute to director Rob Reiner, who was stabbed to death in his home in December, and to Robert Redford, which included a rare stage performance from Barbra Streisand.

Billy Crystal, whom Reiner cast opposite Meg Ryan in "When Harry Met Sally," said Reiner's effect on Hollywood was immeasurable.

"Rob's movies will last for lifetimes because they were about what makes us laugh and cry and what we aspire to be: far better in his eyes, far kinder, far funnier and far more human," he said.

Streisand, 83, who played opposite Redford in the 1973 classic The Way We Were, said she had loved a man who affectionately called her "Babs."

"He was a brilliant, subtle actor," she said. "Bob had real backbone, on and off the screen.

"I called him an intellectual cowboy who blazed his own trail. I miss him now more than ever."