Prime Video's Young Sherlock has confirmed new cast additions for its second season, including Olivia Williams, Sophie Skelton, Indira Varma and Aidan Gillen, alongside the return of lead Hero Fiennes Tiffin and other key regulars. The casting update also clarifies which Season 1 characters will not be back, notably Zine Tseng, whose storyline concluded in the finale, and Joseph Fiennes, whose character's apparent death is now effectively confirmed by the departure of a related cast member.

The four newcomers join Fiennes Tiffin as series regulars, alongside returning cast members Dónal Finn, Natascha McElhone, Max Irons and Holly Cattle. Season 2, directed in its opening episode by co-developer Guy Ritchie, is already filming, with Palermo among the locations. The update follows a strong debut for the series, which drew 45 million viewers in its first 28 days, topped charts in more than 95 countries, and performed particularly well in the UK, India and Germany.