Rosheuvel, Andoh, and Gemmell will all reprise their roles as Queen Charlotte, Lady Agatha Danbury, and Lady Violet Bridgerton, respectively. Additionally, Amarteifio plays young Queen Charlotte, Mylchreest portrays young King George III, and Thomas will make her television debut as young Agatha Danbury.
Other stars in the cast include Michelle Fairley as Princess Augusta; Sam Clemmett as young Brimsley; Freddie Dennis as Reynolds; Richard Cunningham as Lord Bute; Tunji Kasim as Adolphus; Rob Maloney as the Royal Doctor; Cyril Nri as Lord Danbury; and "Bridgerton"'s Hugh Sachs reprising his role as the older version of Brimsley.