The 22-year-old will play the lead role in the four-part drama, based on the 1891 novel by Thomas Hardy.
Hans Matheson (The Virgin Queen, Dr Zhivago) plays her seducer Alec, Eddie Redmayne (Elizabeth: The Golden Age) is her true love Angel, and Jodie Whittaker (Venus) plays her best friend Izzy.
Gavin And Stacey's Ruth Jones will take the role of her mother and Anna Massey (Oliver Twist) features as Mrs D'Urberville.
The adaptation was written by Starter For Ten author David Nicholls and will be produced by David Snodin for BBC Drama Productions.
It will begin shooting in the West Country later this month and airs on BBC One this autumn.