Background: Healthcare financing plays a critical role in determining the equity, efficiency, and resilience of health systems globally. Aim: to systematically evaluate the effectiveness of diverse healthcare financing policies in improving health outcomes, financial protection, and system performance across income settings. Methods: A systematic review was conducted according to PRISMA guidelines, screening 98 records from databases and institutional repositories. Fourteen eligible studies were included, spanning qualitative, econometric, policy review, and quasi-experimental designs. Results: Government-financed models demonstrated superior outcomes, including increases in life expectancy (+1.3 years), reductions in under-five mortality (−8.7%), and lower catastrophic expenditure rates (−3.3 percentage points). Burkina Faso’s gratuity policy led to an 84% drop in OOP among children under five. Tax-based systems in countries like the Netherlands showed the highest technical efficiency (0.6808) and gains of up to 2.5 years in life expectancy per 1% GDP increase in capital health spending. In contrast, SHI models raised expenditure but did not improve outcomes in informal economies. OOP-dominated systems in Nigeria and Sudan saw over 70% household burden, undermining equity. Contextual enablers included digital infrastructure, political stability, and donor alignment; barriers included weak regulation, conflict, and fragmented risk pools. Conclusion: Sustainable health financing reform requires pooled public funding, strong governance, and integration of strategic purchasing to drive equitable and efficient health systems.