As one of the major causes of climate change, there is an urgent need for a fundamental transformation of the food system. Calls for greater sustainability underscore the importance of integrating civil society and the local knowledge of citizens in this transformation process. One increasingly relevant organisation that can actively engage a plurality of actors from across civil society is the Food Policy Council (FPC). In this paper, we explore the potential role of FPCs in sustainability politics to create an alternative food system, with a focus on the co-production of knowledge for policy-making. We propose that the co-production of knowledge requires knowledge inclusion, exchange and transmission, and we focus on the challenges that can arise for FPCs. Our paper shows that bottom-up emerging FPCs constitute a new form of alternative food organisation that can integrate and support the critical capacity of civil society in food system transformation, but also face potential struggles in the co-production of knowledge for sustainable food policy-making. The paper further highlights that co-producing knowledge in and for sustainability transformation is fundamentally a political process, with politics broadly conceived. It not only has relevance for the institutions of formal politics, but emerges in and is intrinsically linked to the grassroots collective action of contentious and prefigurative politics in civil society. FPCs (re)politicise food by combining these various kinds of sustainability politics, which constitutes their transformative potential.