Famously lauded for its dedication to historical accuracy, Corrin was photographed dressed in a near-identical replica of the floral blue frock Princess Diana wore to the ceremony run-through.
The tease comes just days after the 24-year-old rising star was pictured on set at the Savoy Hotel in London.
According to multiple reports, the Netflix team were busy recreating Princess Diana's arrival at the Barnado's Champion Children Awards - an A-list bash which the mother-of-two famously attended throughout the '80s and '90s.
In the shots, Corrin bore striking resemblance to the Princess of Wales in a one-shoulder floral dress which paid tribute to her penchant for all things Catherine Walker.
Corrin, who also boasted the late royal's famous '80s bouffant in the images, can be seen waving to crowds with extras taking on the role of camera-bearing paparazzi surrounding her.
Though it's not the first time the British starlet has excited fans of the Netflix series, as she was photographed filming with O'Connor in Spain last October.
The small screen duo could be seen recreating the former couple's 1983 royal tour of Australia which saw them don near-identical outfits to the get-ups their regal counterparts wore to visit Uluru.
Viewers will be introduced to Diana in the upcoming season with the focus shifting to focus upon Prince Charles' tumultuous love life.
Speaking about taking on the prestigious role, Corrin said in a statement released by Netflix: "Beyond excited and honoured to be joining The Crown for its fourth season."
"I have been glued to the show since the first episode and to think I'm now joining this incredibly talented acting family is just surreal. Princess Diana was an icon, and her effect on the world remains profound and inspiring. To be given the chance to explore her through Peter Morgan's writing is the most exceptional opportunity, and I will strive to do her justice!"
The release date of season four yet to be confirmed (it's not likely to grace our screens until late 2020) but the introduction of Princess Diana is sure to be well worth the wait.