Elizabeth Debicki will play Diana, Princess of Wales, in the final two series of The Crown.
The Night Manager star will replace Emma Corrin in the role for series five and six.
In a statement posted on the official Twitter page of The Crown, the Australian actress 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 known for her role as Jed Marshall in 2016 BBC drama The Night Manager.
The 29-year-old also appeared with Leonardo DiCaprio in The Great Gatsby, Sir Steve McQueen’s film Widows and Marvel’s Guardians of the Galaxy Vol. 2.
She will next be seen in Christopher Nolan’s highly-anticipated new film Tenet, which is set to be the biggest release since UK cinemas reopened from lockdown when it hits the big screen later this month.
Earlier this week, it was announced that Jonathan Pryce will take over from Tobias Menzies to play the Duke of Edinburgh for the final two series of the big-budget show.
The 73-year-old admitted that taking on the role was a “daunting prospect”.
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 series will take the monarch’s reign into the early 21st century, but before then may deal with several royal crises including Prince Charles‘s split from Diana – part of the Queen’s “annus horribilis” of 1992.
That year also saw Prince Andrew separate from Sarah, Duchess of York, the fire at Windsor Castle and Princess Anne’s divorce from Captain Mark Phillips.
Other episodes are likely to deal with Diana’s death in 1997 and those of Princess Margaret and the Queen Mother within weeks of each other in early 2002.
The fourth series of the royal Netflix drama features X-Files star Gillian Anderson as Margaret Thatcher and will air later this year.