The blonde beauty brought a surprise date along to the glamorous affair, her proud mum Sarie Kessler.
Margot, 27, leads the Aussie contingent at the Oscars with her nomination for Best Actress for her portrayal of American Olympic ice-skater Tonya Harding in the film I, Tonya. Margot was also a producer on the film.
The white gown, although seemingly simple in its silhouette, took the famous designer 600 hours to craft, reports Instyle. The corset bodice features a 3D band of crystal tubes filled with with camellias, a favourite flower of Coco Chanel.
Margot completed her look with Chanel accessories – a statement ring and earrings in 18 carat white gold and diamonds.
During a visit on The Project, Margot recalled the thrilling moment she discovered she received her first Oscars nomination for the film I, Tonya.
The nominations came rolling in just as the actress was thinking of leaving an after party thrown for the film's Australian premiere. First the editor of I, Tonya, Tatiana S. Riegel, was nominated. Then Allison Janney for best supporting actress.
And then came the blonde beauty's big moment…
"Then someone plugged their phone into the DJ booth so it was really loud just when they announced my name," she told The Project panel. "The whole room just went rahhhhhhh and we all started screaming and my mum was crying. It was amazing."
It's the first of such nominations for the Queensland-born actress, arriving just five years after her breakout role in Martin Scorsese's The Wolf of Wall Street. Since then, she's tackled starring roles in the likes of Focus, Whiskey Tango Foxtrot, The Legend of Tarzan and Suicide Squad.
Margot is up against some fierce female's in her category for Best Actress in a Leading Role including:
Sally Hawkins, The Shape of Water
Frances McDormand, Three Billboards Outside Ebbing, Missouri
Saoirse Ronan, Lady Bird
Meryl Streep, The Post