By using country-level data collected from 183 countries worldwide, this ecological study aimed to investigate the association between greenness and depressive disorders globally. We used the normalized difference vegetation index (NDVI) to estimate greenness exposure. The disability-adjusted life years (DALY) provided by the World Health Organization was used as a proxy for health burden due to depressive disorders. A linear mixed model algorithm was used to assess the association after controlling for pertinent covariates. Stratified analyses were then conducted to determine the effects of greenness on different groups, stratified by age, sex, economic status, urbanization level, and continent, respectively. The main findings show a significant negative association between greenness and depressive disorders with an NDVI coefficient of -0.58 (95% CI: -1.06, -0.10) for change in DALY. The results from the subgroup analyses suggested significant beneficial effects of greenness on depressive disorders across sex, various age groups, and especially for those aged less than 49 years, with low-income and/or those living in highly urbanized countries as well as Asian, African, and American regions. In short, the findings can add additional evidence of the possible benefits of green exposure on mental health and further reduces the risk of depressive disorders.