Though the level of public and private health expenditure per capita in Southeast Asia is comparatively below the level of health expenditure in Organisation for Economic Co-operation and Development (OECD) countries, the former has higher rates of under-five and non-communicable disease mortality rates than the latter. Similarly, life expectancy at birth is considerably higher in OECD compared to Southeast Asia, despite the global progress in recent decades. This study examines the dynamics of public and private health expenditure on health outcomes in Southeast Asia, vis-a-vis two of the Sustainable Development Goals targets. The techniques of fixed effect, random effect and feasible generalised least squares methods are used to obtain robust estimates. Furthermore, the analysis dives deep into the analysis of country-specific impacts of public and private health expenditure on health outcomes using the technique of seemingly unrelated regression. Estimates show that, across Southeast Asia, public health expenditure alone contributes to improving life expectancy at birth, lower level of under-five and non-communicable disease mortality rates. Unlike public health expenditure, private health expenditure contributes to better health outcomes only in Brunei and Singapore but not across the countries of Southeast Asia. The implications of the findings and possible future research areas are highlighted further.