It is widely recognized that there is a global need for a transition towards more sustainable forms of agriculture. In order for such a transition to be socially sustainable, its input (problem and goal formulation), output (policy instruments), and throughput (processes) need to be perceived as legitimate. However, we currently know relatively little on how to legitimize normatively shaped transition processes and their outcomes. We aim to address this knowledge gap by examining how the governance of agricultural transitions can be shaped to improve the perceived legitimacy of the transition. Through a combined lens of normative and sociological approaches to legitimacy we investigate the English post-Brexit agricultural transition as a crucial case-study. Building on a policy analysis and semi-structured interviews we find that in order to create perceived legitimacy of agricultural transitions, both in the English case and for agricultural transitions generally, clarity and diversity in design is essential. In addition, in order to take account of the normative and political nature of agricultural transitions, our study highlights the importance of a broad problem formulation, a diverse mix of instruments, and a process that is transparent and includes stakeholders in a meaningful and equal way. We conclude that a combined lens of normative and sociological legitimacy forms a useful framework for future research to critically evaluate the normative and power dimensions of transition processes. In addition, it can support governments in their efforts to develop policies for agricultural sustainability transitions that will be accepted by society.