In this essay, we review eight prominent critical traditions inspired by Marxism and advance a vocabulary to theorise alternative organising as a means to achieve postcapitalism. By challenging the characterisation of alternative organising within capitalist relations as ‘ambiguous’, we argue for re-embedding this literature into the critique of capitalism. We aim to develop a new postcapitalist perspective for actionable organisational knowledge. We pose two research questions: (1) How can the economy and society be reconceptualised postcapitalistically in theory? (2) how can these concepts be politically mobilised for postcapitalist organising? As a contribution, by reintroducing critical political economy into the scholarly conversation on alternative organising, we demonstrate how postcapitalist knowledge can be productive for performative social change and for envisioning novel forms of organising differently. Our study not only offers a fresh reconceptualisation of the economy and society but also introduces theoretical possibilities for the politics of alternative organising.