Action on the social determinants of health (SDH) through intersectoral policymaking is often suggested to promote health and health equity. This paper argues that the process of intersectoral policymaking influences how the SDH are construed and acted upon in municipal policymaking. We discuss how the intersectoral policy process legitimates certain practices in the setting of Danish municipal health promotion and the potential impact this can have for long-term, sustainable healthy public policy. Based on ethnographic fieldwork, we show how the intention of intersectoriality produces a strong concern for integrating health into non-health sectors to ensure productive collaboration. To encourage this integration, health is often framed as a means to achieve the objectives of non-health sectors. In doing so, the intersectoral policy process tends to favor smaller-scale interventions that aim to introduce healthier practices into various settings, e.g. creating healthy school environments for increased physical activity and healthy eating. While other more overarching interventions on the health impacts of broader welfare policies (e.g. education policy) tend to be neglected. The interventions hereby neglect to address more fundamental SDH. Based on these findings, we argue that intersectoral policymaking to address the SDH may translate into a limited approach to action on so-called ‘intermediary determinants’ of health, and as such may end up corrupting the broader SDH. Further, we discuss how this corruption affects the intended role of non-health sectors in tackling the SDH, as it may impede the overall success and long-term sustainability of intersectoral efforts.