Corrin, best known for appearances in Netflix series The Crown and the streaming giant's feature-length Lady Chatterley's Lover, wore a from fashion brand Miu Miu's Fall-Winter 2023 collection at the festival on Sunday, while in the city to attend the Italian label's 'Women's Tales' film event.
Corrin's outfit consisted of a green knitted cardigan with matching green underpants, a marked departure from what you might expect to see on the red carpet.
However, Corrin is not the first celebrity to step out in their underwear recently.
Supermodel Bella Hadid was photographed wearing what appeared to be boxer briefs in the street last fall, and Lil Nas X wore just a metallic G string to the Met Gala in May.
Corrin, who uses they/them pronouns, was nominated for a Primetime Emmy in 2021 for their portrayal of Princess Diana in The Crown, in the outstanding lead actress in a drama series category.
The 2023 Venice Film Festival, which started on Wednesday, sees the premieres of new films from Bradley Cooper, Sofia Coppola, Yorgos Lanthimos, Michael Mann and Ava DuVernay.
The festival's opening film was Comandante, an Italian period drama from director Edoardo De Angelis starring Pierfrancesco Favino, who appeared in The Traitor.