Through a case study of a rent strike against a real estate investment trust in a working‐class neighbourhood in Hamilton, Ontario, this article asks how we might understand class and class struggle against financialized gentrification in a post‐industrial context. While class has been central to gentrification literature, working‐class experience and struggle have often been ignored or conceptualized in a way that precludes agency. New research on financialization of housing often focuses on struggles but has so far paid limited attention to class. In this article I draw on Italian operaismo (workerism) and its concept of class composition to contribute to the current debate by suggesting that financialized gentrification and struggles against it might contribute to a recomposition of the urban working class. Through a qualitative account of the 2018 East Hamilton rent strike, I analyse this struggle as two moments of class composition in the sphere of social reproduction. First, the extraction, exploitation and displacement pressure tenants experienced is analysed through the lens of technical class composition. Second, the rent strike itself is analysed as an expression of political class composition involving a confrontation of urban capital, a politicization of housing precarity, and the building of collective, autonomous power.