Emma Corrin is playing Diana on the drama's upcoming fourth season, but Debicki will take on the part for what's sure to be the character's most dramatic chapters. Seasons five and six are expected to be the show's final seasons. No premiere date of season four has yet been announced.
"Princess Diana's spirit, her words and her actions live in the hearts of so many," Debicki said on Twitter. "It is my true privilege and honor to be joining this masterful series, which has had me absolutely hooked from episode one."
Debicki, a 29-year-old Australian actress, is seen as a rising star after breakout performances in Steve McQueen's Widows. She also stars in Christopher Nolan's upcoming thriller Tenet.
- AP