This study examines the effects of various factors, including socioeconomic status, built environment, access to healthcare, educational level, social participation, and economic stability, on older adults' psychological health. The current study analyzed a nationally representative sub-sample of 2,577 respondents aged 50 and above from the World Health Organization's Study on Global AGEing and Adult Health (WHO SAGE) Wave 2. WHO SAGE Wave 2 is cross-sectional data collected via in-person structured interviews. Ordinal least square (OLS) was used to measure the average effect of social determinants of health (SDoH), and quantile regression analysis was used to determine the effects of SDoH on older adults' psychological health at different quantiles, specifically 10th, 50th, and 90th percentiles. Significant determinants of psychological health across all quantiles included age, healthcare access, marital status, economic stability, and neighborhood and built environment. However, the degrees of significance for residence, gender, educational level, chronic diseases, and social participation varied between quantiles, showing differing effects on older adults with high or low psychological health. Religion was insignificant across all quantiles. This study highlights the need for governments and public health agencies to develop targeted interventions and strategies that support the psychological well-being of older adults in the country.