[3] Hainsworth made her television debut in the 2016 with small roles in the BBC One miniseries One of Us (also known as Retribution) as Maddy and the ITV drama In Plainsight.

She took over the lead role of Orla from Melissa Allan in the stage adaptation of Our Ladies of Perpetual Succour when it moved to the Duke of York's Theatre in 2017.

Hainsworth played Michelle McCullen and Louise Graham in the BBC One miniseries Wanderlust (2018) and The Victim (2019) respectively, as well as Abigail Warren in the second series of Harlots.

For her performance as Hermia in A Midsummer Night's Dream at the Bridge Theatre, Hainsworth was nominated for a 2019 Ian Charleson Award.

In 2022, Hainsworth starred opposite Amelia Clarkson in the BBC Three horror series Red Rose as Rochelle Mason [4] and alongside Jaeden Martell in the Netflix teen band film Metal Lords as Emily Spector.