Mental disorder accounts for a third of global disease burden (years lived with a disability), with associated global annual economic costs projected to exceed US$6 trillion by the year 2030. Effective public mental health (PMH) interventions exist to treat mental disorders, prevent associated impacts, prevent mental disorders from arising, and promote mental well-being and resilience. However, only a minority of those with mental disorders receive treatment with far less coverage in low- and middle-income countries. There is even less coverage of interventions to prevent associated impacts and negligible coverage of interventions to prevent mental disorders, or promote mental well being and resilience. The implementation gap breaches the right to health, has widened since the COVID-19 pandemic, and results in population-scale preventable suffering, broad impacts, and associated economic costs. PMH practice takes a population approach to improve coverage, outcomes, and coordination of PMH interventions. This supports efficient, equitable, and sustainable reduction of mental disorders and the promotion of the mental well-being of populations. Required actions to improve the implementation of PMH interventions include: 1) Assessment of PMH need to inform policy, choice of implementable PMH interventions, transparent decisions about coverage and required resources across different sectors, implementation to agreed level, and regular evaluation of coverage and outcomes; 2) Coordinated advocacy and leadership; 3) PMH training and improved population knowledge; 4) Settings based and integrated approaches, digital technology, maximizing existing resources, focus on high impact PMH interventions, and inclusion of mental disorders in national insurance or reimbursement schemes; 5) Use of legislation and a rights approach; and 6) Implementation research. Improved implementation results in broad impacts, associated economic benefits contributing to economic development, and achievement of a range of policy objectives.