Food systems are made of a myriad of actors, visions and interests. Collaborative governance arrangement may foster their transformation towards greater sustainability when conventional means, such as state-oriented planning, technological developments or social innovations provide insufficient impetus. However, such arrangements may achieve transformative results only under certain conditions and in specific contexts. Despite an abundant literature on participatory schemes, the success for collaborative governance arrangements remains partially understood and deserves academic attention, in particular in the field of food systems reform. This article provides an in-depth analysis of an empirical case study in the Walloon Region (Belgium), where the administration for sustainable development initiated a six-month participatory process to collectively construct a roadmap towards a sustainable regional food system. The article explores the extent to which the process has allowed transformative voices to emerge, and assesses whether the outcome provides a promising tool for adopting a transformative policy at the regional scale. It argues that the facilitation process insufficiently attenuated existing power relations and highlights key underlying factors (including time, resources, expertise and coalition building) that, like in classical negotiation settings, strengthen or weaken specific actors. It discusses the link between the results of the participatory process and the potential for policy-makers to build upon these to guide further the region’s food system towards a sustainable future.