BackgroundMajor Depressive Disorder (MDD) poses significant public health challenges globally and in Southeast Asia, with substantial impairment and disease burden. Understanding its prevalence and associated risk factors is crucial for effective intervention. MethodsThis study aims to describe the prevalence shifts, correlates, and comorbidities of MDD in Singapore. Data were collected from the second Singapore Mental Health Study (SMHS 2016), a national cross-sectional survey comprising 6126 adult residents. The WHO Composite International Diagnostic Interview assessed MDD and comorbidities. Statistical analyses, including logistic regression, were conducted to examine the associations and trends. ResultsThe lifetime weighted prevalence of MDD in SMHS 2016 was 6.2 %, with an overall increase from 5.8 % in 2010. Significant associations were found between MDD and age, marital status, and comorbid physical disorders. Young adults and divorced/separated individuals exhibited higher MDD prevalence. Chronic pain was significantly associated with MDD. LimitationsThe study's cross-sectional design limits causal inference, and selective non-response might affect prevalence estimates. However, the study benefits from a large, nationally representative sample and standardized methodologies. ConclusionsYoung and middle-aged adults, and divorced/separated individuals demonstrate elevated MDD prevalence, warranting targeted interventions. Individuals with comorbidities, particularly chronic pain, constitute a high-risk and vulnerable population. Comprehensive assessment and treatment plans should involve multidisciplinary teams and integrated care approaches to better address the complex needs of these individuals. Our study also highlights specific interventions for schools, families, communities, and workplaces. Despite Singapore's relatively low prevalence compared to Western nations, MDD remains cross-culturally valid emphasizing the need for early intervention and preventive public health measures.