Migration and displacement are reshaping societies and economies with profound implications for health equity and universal health coverage (UHC). In this Viewpoint, we review the unique health challenges faced by migrants and displaced people, as well as the limitations of current UHC policies and financing arrangements. We propose a cosmopolitan approach to UHC, grounded in global solidarity and structured around four pillars: supranational financing, integrated cross-border care, harmonised legal frameworks, and long-term investment in inclusive health systems. We also explore what this approach could mean practically for regional or global financing mechanisms and sources of funding, including progressive contributions and the integration of health into climate finance. Achieving equitable and effective UHC in a world shaped by mobility and crisis requires global thinking and collective action. We call for a reimagining of UHC via a cosmopolitan approach, which offers a pathway to reframe health and wellbeing as a shared right and responsibility, transcending national borders.