<p>This review synthesizes global trends, persistent challenges, and actionable pathways for overhauling public mental health systems, with a particular focus on low- and middle-income countries (LMICs). Thematic analysis of our review revealed that mental health disorders now affect nearly one in eight people worldwide, yet up to 75% of those in LMICs receive no treatment due to stigma, underfunding, workforce shortages, and fragmented systems, perpetuating a widening “treatment and care gap.” Social inequities, harmful cultural norms, conflict, climate change, and gender disparities further amplify the risk and economic burden, projected to exceed US$6 trillion by 2030. Innovative financing approaches, including public-private partnerships and models from countries such as Norway and Australia, offer promising strategies for sustainable investments. The COVID-19 pandemic intensified mental health challenges but also raised global awareness, with leaders such as the United Nations Secretary-General and the United States Surgeon General foregrounding mental health crises in the public consciousness. Advocacy initiatives, including the FundaMentalSDG campaign, Lancet Commissions, Global Mental Health Action Network, and Global Mental Health Peer Network, have been pivotal in elevating mental health within the Sustainable Development Goals (SDGs) and linking it to social determinants. Emerging solutions include rights-based frameworks that emphasize participation and anti-discrimination, scaling up task-sharing and expanded roles for non-specialists through programs such as the World Health Organization’s Mental Health Gap Action Programme, community-based interventions like Zimbabwe’s Friendship Bench, and integration of mental health into primary care with dedicated counsellors, structured referral pathways, and digital innovations promising improved access and personalization. Sustained progress requires intersectoral collaboration across health, education, labor, and social sectors; embedding mental health into national health information systems; and investing in culturally adapted promotion and prevention interventions throughout the life course. Strengthening political commitment, global-local leadership, financing frameworks, and workforce capacity, particularly through continuous professional development and lived-experience participation, will accelerate progress toward the SDGs, underscoring the imperative for equitable financing and sustained political will globally.</p>