The concept of the ‘commercial determinants of health’ (CDOH) has been developed by public health researchers as a way to describe the political economy of corporations and the impact of their practices on health, social inequalities and climate change. In this analysis, we assess the conceptual work that has developed this field and the influence of the more established ‘social determinants of health’ models. We highlight the dominance of epidemiologic and biomedical concepts on understandings of structure and agency in the CDOH literature and argue that the terminology of ‘risk factors’, ‘drivers’ and ‘pathways’ reflects an agent-centred approach. We suggest that, as a result, there is a tendency to overlook the importance of political institutions in shaping the exercise of corporate power. Our analysis seeks to ‘bring institutions in’ to CDOH research, using the empirical cases of Health in All Policies and Better Regulation in the European Union to highlight how institutional contexts shape political legitimacy and accountability, and in turn the strategies of corporate actors. Institutionalist approaches, we argue, have the potential to develop and expand understandings of CDOH by opening the black box between agency and structure.