The upcoming six-episode drama delves into the treacherous underbelly of illicit boxing in the smog-filled streets of 1880's Victorian London, and will be available for streaming on Disney+.
The Oscar-nominated actress, 28, and the Peaky Blinders star, 29, were first romantically linked in September, but have not publicly confirmed their relationship.
It was confirmed in June that the Peaky Blinders' original writing and directing team would be returning alongside Cillian for a Netflix film adaptation of the hit series.
There are a whopping six seasons for fans to binge with an impressive cast, including Peaky Blinders star Finn Cole, Ellen Barkin who played Helen Cruger in Sea Of Love.