The reported prevalence of depressive symptoms (depression hereafter) among older adults varied widely across different studies. This was a meta-analysis to systematically examine the global prevalence of depression among older populations and its associated factors.A systematic literature search was performed in PubMed, EMBASE, PsycINFO, and Web of Science. Due to the differences in demographic and clinical characteristics between studies, random-effects model was used to calculate the pooled prevalence of depression and its 95% confidence interval (95% CI).In total, 55 studies with 59,851 individuals met the study criteria and were included in the analyses. The overall prevalence of depression was 35.1% (95%CI: 30.2-40.4%). Subgroup analyses revealed that different sampling methods (Q=10592.49, p = 0.037), Geriatric Depression Scale versions (Q=13712.55, p < 0.001) and income levels (Q=14.028, P < 0.001) were significantly associated with the pooled prevalence of depression in older adults. In the meta-regression analyses, time of survey (B=0.012, z = 2.30, p = 0.029) was positively associated, and mean age (B=-0.018, z = 2.10, p = 0.044) was negatively associated with the prevalence of depression in older populations. The funnel plot and Egger's test did not reveal any significant publication bias (Egger's test: t = 1.93, p = 0.059).This meta-analysis found that over a third of older populations globally had depression. Effective preventive measures, regular screening and timely interventions are needed to address this highly prevalent public health problem among older adults.