Hannah John-Kamen was born in Anlaby, East Yorkshire, daughter of a Nigerian forensic psychologist and a Norwegian model. She graduated from the Royal Central School of Speech and Drama.
John-Kamen began his career in 2011 giving voice to a character in the video game Dark Souls. Between 2011 and 2012 she appeared in minor roles in numerous television series, including Misfits, Black Mirror and The Hour.
In 2012 she won the lead role of Viva in Viva Forever, a musical based on the Spice Girls’ songs. From 2015 she is the protagonist of the television series Killjoys, broadcast on Syfy.
In 2017 she entered the cast of the reboot of Tomb Raider alongside Alicia Vikander, the movie Ready Player One by Steven Spielberg alongside Olivia Cooke and the film Marvel Cinematic Universe Ant-Man and the Wasp, in which she played the villain Ghost.
Set in a near-future dystopian Earth, the population spends most of its time in an interconnected virtual space called the OASIS. When its founder dies and bequeaths ownership to the first person to find a hidden treasure within by playing games and solving puzzles, a race ensues between a young man and his friends, and an evil megacorporation that wants to control OASIS for themselves.