Australian star Nicole Kidman inadvertently upstaged one of the world’s richest men in an embarrassing moment on the Oscars red carpet.

The statuesque Baby Girl actress was filmed gliding behind Amazon founder Jeff Bezos and his wife Laura Sanchez as they posed for photographers at the Vanity Fair afterparty.

In the photobombing moment, Kidman walked through Bezos and Sanchez’s shot to take up her position for the cameras.

Photographers who had been shooting the couple quickly turned their frenzied attention away from Bezos and honed in on Kidman in her glittering golden gown.

Even Bezos and Sanchez stopped what they were doing to turn and watch the Hollywood icon glam it up for the flashing cameras.

Fans shared the photobombing footage on social media, saying Kidman “stole the show” from the fourth richest person in the world, who is worth about $US224 billion ($316 billion).

“This queen walked right by and said the movie star is here,” said one comment on Instagram.

Another noted: “Nicole Kidman just walked by and reminded everyone who the real royalty of Hollywood is.”

Nicole Kidman changed into a golden Chanel gown after the Oscars ceremony. Photo: AAP

Kidman was wearing her second outfit of the night for the after-party, a shimmering long-sleeved Chanel gown that matched her loose golden tresses.

Earlier for the 98th Academy Awards ceremony she wore another Chanel gown — a pale corset-style bustier embellished with feathers and grey-and-white crystal detailing.

Kidman was also a presenter during the awards ceremony, presenting the Best Picture Oscar to One Battle After Another with former Moulin Rouge co-star Ewan McGregor.

Actress Rose Byrne, a frontrunner to win best actress, was among several Australians who missed out on cinema’s biggest night.

Nominated for her role as a struggling mother in the indie film If I had Legs I’d Kick You, Byrne lost to Jessie Buckley for her portrayal of playwright William Shakespeare’s wife in Hamnet at the awards.

Nicole Kidman and Ewan McGregor presented the final award of the evening. Photo: AAP

Sydney-born Byrne had been touted as a favourite in a strong field that included Kate Hudson, Renate Reinsve and Emma Stone, after claiming the best actress prize at four key pre-Oscars events, including the Golden Globes.

Kidman and Cate Blanchett are the only Australians to have won Oscars in the coveted best actress category.

Byrne, one of many celebrities who stunned on the red carpet, arrived for cinema’s night of nights in a timeless custom black Dior gown embroidered with colourful beaded flowers.

Another Australian, Queenslander Jacob Elordi, nominated in the best supporting actor category for playing the creature in Frankenstein, was beaten by Sean Penn who won his third Oscar for his role as a racist soldier in One Battle After Another.

Australian musician Nick Cave, nominated for best original song on Train Dreams, which stars Australian actor Joel Edgerton, lost to the song Golden featured on KPop Demon Hunters.

Costume and production designer Fiona Crombie was another Australian to go home empty-handed, denied in the best production design category for her work on Hamnet, and losing out to Frankenstein.

One Battle After Another, the sweeping Paul Thomas Anderson-helmed comic political drama, starring Leonardo DiCaprio, was the night’s big winner, claiming six golden statuettes, including best picture, best director, and best adapted screenplay.

In other major categories, best actor went to Michael B Jordan for his dual role as twins in Sinners, which won four Oscars, while Amy Madigan prevailed in the best supporting actress category for her work as a witch in the horror film Weapons.

-with AAP