Barker spent her early childhood in London and Winchester before growing up in Glasgow until her teen years.
[2] Her parents eventually separated, and Barker moved to Church Fenton, a village in the Selby District of Yorkshire, with her mother and stepmother.
[3][4] She planned to study international relations at the London School of Economics after taking a gap year, but decided to pursue drama instead.
[6] She was discovered by Royal Shakespeare Company director Phillip Breen, who cast her as Mary in the 2016 York Mystery Plays and helped her get signed with an agency.
[14] Barker was hospitalised in 2022 for mental health reasons, stating that she was "really unwell for a really long time" and had "all this intergenerational trauma bundled up inside" her.