Two actors, Rufus Kampa, 16, and Ed McVey, 21, will play William, while Meg Bellamy will take on the role of Kate Middleton, according to various US media outlets.
The announcement comes ahead of the launch of series five of the popular royal-related drama, which is due to return in November.
Both McVey and Bellamy are relative unknowns, and were reportedly selected for the world-famous Netflix show after submitting self-taped auditions for a casting call put out on social media.
McVey is an alumnus of Drama Centre London, and has worked in several theatre productions but is yet to make his professional screen debut, The Times reported.
Bellamy has no professional acting experience and is understood to have worked at Legoland amusement park, according to The Daily Telegraph.
The pair will play William and Kate as young adults during the time that they met at St Andrews University in 2001.
Imelda Staunton takes over the role of the Queen from Olivia Colman, while Jonathan Pryce replaces Tobias Menzies as the Duke of Edinburgh and Lesley Manville will be Princess Margaret, following in the footsteps of Helena Bonham Carter.
It will see Dominic West star as Charles and Elizabeth Debicki as Diana, Princess of Wales.
The Wire star West takes over the role of Charles from Josh O’Connor, while The Night Manager actress Debicki replaces Emma Corrin.
It was previously revealed that series five of the show would delve into the Diana’s now infamous Panorama interview with journalist Martin Bashir.
The Crown was due to end after its fifth series, but the show’s creator and writer Peter Morgan later said it will be extended to include a sixth series.