The 13-year-old will make his on-screen debut in season five, starring alongside his real-life father Dominic, who takes over the role of Prince Charles, and Tenet's Elizabeth Debicki, who will portray Princess Diana.
Senan West is believed to have caught the attention of The Crown's producers after sending in an audition tape, Variety reported.
RadioTimes.com has contacted Netflix for comment.
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Season five of The Crown is predicted to cover the early to mid-'90s, up until Princess Diana's death in 1997, at which point Prince William was just 15 years old.
The upcoming series will mark the hit historical drama's third round of cast changes, with Harry Potter star Imelda Staunton inheriting the role of Queen Elizabeth II from season three and four's Olivia Colman and season one and two's Claire Foy.
Earlier this year, Netflix confirmed that Jonathan Pryce and Lesley Manville would be taking on the roles of Prince Philip and Princess Margaret respectively, while Jonny Lee Miller and Olivia Williams are set to play Prime Minister John Major and Camilla Parker Bowles.
Production on season five has already begun, with Netflix sharing a first look at Staunton as the reigning monarch back in July.
Discover the real history behind The Crown from our friends at History Extra.
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