She is known for her roles as a bounty hunter in the Syfy television series Killjoys (2015–2019), Ava Starr / Ghost in the superhero film Ant-Man and the Wasp (2018) and Thunderbolts* (2025), the title character in the Netflix mystery miniseries The Stranger (2020), and Jill Valentine in the film Resident Evil: Welcome to Raccoon City (2021).

Hannah John-Kamen was born in England, the daughter of a Norwegian fashion model mother and a Nigerian forensic psychologist father.

She went on to make appearances in episodes of television series Misfits (2011), Black Mirror (2016), Whitechapel (2012), The Syndicate (2012), The Midnight Beast (2012) and The Hour (2012).

[6] The Daily Mirror, however, praised John-Kamen's performance and called it a "shame" that she and the rest of the cast were "let down by a clichéd plot and leaden dialogue".

[14][15] John-Kamen enjoys playing the piano and is trained in various dances such as ballet, cabaret, jazz, salsa and tap.