Hesmondhalgh is a Labour Party member. In August 2015, she endorsed Jeremy Corbyn's campaign in the Labour Party leadership election. She tweeted: "Proudly supporting Jeremy Corbyn in the Labour leadership contest." She campaigned for Corbyn as party leader in the 2017 UK general election. In May 2017, speaking at Labour's general election campaign launch in Manchester, she said: "I realised the Labour party and its core values would finally be in line with my own deeply held socialist beliefs about equality, justice and peace."