Global mental health diplomacy must prioritise a human rights-based approach to integrate mental health into the international agenda through cooperation and advocacy. With over 75% of individuals with mental ill health in low-income and middle-income countries (LMICs) lacking access to care, immediate action is essential. Despite increasing recognition of mental health globally, the consistent application of a rights-based approach remains limited. Viewing mental health as a core element of public health fosters international cooperation, enhances resilience, broadens access, and strengthens mental health rights.