Quentin Tarantino's "Once Upon a Time... in Hollywood" backed up its Oscars front-runner status by scooping best picture at the Critics' Choice Awards on Sunday.

The high-profile awards in Santa Monica - which also honor the best of television - are seen as a barometer for the all-important Oscars, for which nominations are due out Monday.

"I agree with the critics for the very first time," joked Tarantino as he collected Brad Pitt's best supporting actor prize, before returning to the stage for the evening's top award.

Tarantino's love letter to 1960s Tinseltown, starring Leonardo DiCaprio and set against the backdrop of the Manson family murders, also won for best original screenplay and production design.

With the Golden Globe best comedy prize already secured, the movie appears well-placed for next month's Oscars.

British director Sam Mendes and South Korean auteur Bong Joon-ho shared honors after the closely watched best director category ended in a tie.

Mendes' sweeping World War I odyssey "1917" also took home editing and cinematography awards, while Bong's black comedy "Parasite" was named best foreign-language film. 

"Today I was just enjoying the vegan burger and trying to enjoy the ceremony," joked Bong as he collected his prize.

The awards had emulated last week's Globes by serving a plant-based menu, to boost environmental awareness.

And on the acting front, most of the prizes followed the favorites established by the Globes.

Joaquin Phoenix and Renee Zellweger further bolstered their Oscar odds by picking up the top acting gongs for "Joker" and "Judy".

Laura Dern and Pitt also continued their supporting actor sweeps, earning further honors for their turns in "Marriage Story" and "Once Upon a Time..."

Eddie Murphy received a massive standing ovation as he collected the event's lifetime achievement award, before his blaxploitation biopic "Dolemite Is My Name" won best comedy.

Robert De Niro expressed surprise as he and Al Pacino collected the best acting ensemble prize for "The Irishman".

"I wasn't expecting it, frankly, at this point," he said, after the crime epic - an early Oscars frontrunner - was shut out at the Globes and missed out on several anticipated acting nominations elsewhere.

"Fleabag" topped the television awards, collecting three gongs including best comedy to continue its impressive award season run. "Succession" won best drama series.

Ava DuVernay thanked Netflix for "letting a black woman do her thing" as "When They See Us", the true story of five ethnic minority teenagers wrongly accused of raping a New York jogger, won best limited series. 

"Thank you to the critics for finally letting us take the stage," she added, after the acclaimed show fared poorly at the Emmys and Globes. Jharrel Jherome dedicated his acting win to "the 'Exonerated Five'."

The annual event held by the Critics Choice Association at an airplane hangar near Los Angeles was again hosted by actor Taye Diggs.