The Night Manager actress will take over the role from Emma Corrin for series five and series six.
She said: “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 is best known for her role as Jed Marshall in the 2016 BBC drama The Night Manager and has also appeared in Sir Steve McQueen’s film Widows, and Guardians of the Galaxy: Vol. 2.
She will next be seen in Christopher Nolan’s highly anticipated new film Tenet.
Earlier this week it was announced that Jonathan Pryce will play the Duke of Edinburgh for the final two series of the big-budget Netflix drama, taking over from Tobias Menzies.
Imelda Staunton has previously been named as the next Queen and Lesley Manville cast as Princess Margaret. They will replace Olivia Colman and Helena Bonham Carter respectively, who will bow out after the upcoming fourth series.
The fifth and sixth instalments will bring the drama into the 21st century.
