"When Peter Morgan asked me to do it I was quite overwhelmed, but I've had a little bit of time to process it now," the actress said on "Good Morning America" on Thursday. "I think that I'm actually just incredibly excited to do it, and she's such an incredibly important figure."
"She was such a remarkable human being and so the idea of stepping into it is daunting but very exciting," Debicki added.
Elizabeth Debicki will play Princess Diana in the final two seasons of The Crown (Seasons 5 and 6). pic.twitter.com/Z3CjHuJ56B— The Crown (@TheCrownNetflix) August 16, 2020
The hit Netflix series has followed the royal family through several time periods, using different actors to play its characters as the show spans from the 1940s to the 1980s.
Princess Diana will be introduced in the upcoming fourth season with actor Emma Corrin; "X-Files" veteran Gillian Anderson will play Margaret Thatcher in the fourth season as well. That season will debut on Nov. 15.
With season five filming in June 2021, cameras won't begin rolling on the sixth and final season until 2022.
"Princess Diana's spirit, her words and her actions live in the hearts of so many. It is my true privilege and honour to be joining this masterful series, which has had me absolutely hooked from episode one," Debicki said in an announcement when the casting news was revealed last month.
In the meantime, here's what you need to know about Debicki:
1. She was born in France and raised in Australia: The 29-year-old actress has an international background. Born in Paris to a Polish father and Australian mother, Debicki's family moved to Australia when she was young.
"We have a lot of family in Europe, and Paris still feels like home," she told The Age in 2013. However, her French isn't perfect, she added.
"Last time I was in Paris, I'd been there about 10 minutes and I strolled down to the bakery and had a panic attack about ordering a quiche. I thought, 'Oh god, I can't remember how to say anything!'" she recalled.
2. Performing is in her blood: Debicki's parents are classically-trained dancers, and she was too. However, by 16, Debicki had grown to over 6 feet tall and pivoted from ballet to acting. She trained at the Victorian College of the Arts.
"I love dance and I still take classes; that's really important for my sanity. I think once a dancer, you always have to move. But I was really drawn towards words," she told The Age. "It's kinda murky. I can't see a clear distinction between dance and acting. It is the same part of my brain firing. I just liked talking and words."
3. She landed a big break early: In 2013, Debicki made headlines for her head-turning role as Jordan Baker in Baz Luhrmann's "The Great Gatsby."
"I flew to L.A. for about 48 hours, met Baz, did an audition with Tobey at the Chateau Marmont and then I went home," Debicki told HuffPost at the time. "A month later, Baz called me up and said, 'Would you like to be in our little show?' Very Baz."
4. She does not use social media or take selfies: "I've always been a private person. I feel like the thing I want out in the world is my work and I've always believed – and it's the way I approach my work – that me and the work are separate. I think that people with social media can blur it so beautifully, and I respect that, but it's not really how I am and I just want the work to speak and people to receive it the way they will without anything influencing it. I just want people to know me for my work," she told told Vogue Australia in 2018. .
5. She has other projects in the works: The actress will be seen next in Christopher Nolan's oft-delayed "Tenet" and will voice Mopsy Rabbit in "Peter Rabbit 2: The Runaway."
ABC News' Lesley Messer contributed to this report.