BACKGROUND: In the context of growing concerns about seafarers' mental health during the COVID-19 pandemic, this study aimed to assess the prevalence and associated factors of psychosocial distress among seafarers of ocean-going vessels during the current health emergency. METHODS: This cross-sectional study was conducted among 470 multinational seafarers working on two oil tanker international shipping companies. Psychosocial distress was assessed by using Depression-Anxiety-Stress Scale (DASS-21). General Health Questionnaire-12 (GHQ-12) and Zung Self-Rating Anxiety Scale (SAS) were used to assessed genral psychiatry disorders and self-rate anxiety. Perceived health status was assessed by a single-item question. Multivariate logistic regression was used to determine the association between demographic and work-related variables with mental health outcomes. RESULTS: Overall, 439 out of 470 invited seafarers with a mean age of 34.5 (SD: 8.05) participated in this study (participation rate: 93.4%). The prevalence (95% confidence interval) of depression, anxiety, stress, self-rated anxiety, general psychiatric disorders, and poor perceived health status was 12.3% (9.4-15.7), 11.6% (8.7-15.0), 5.9% (3.9-8.5), 2.1% (0.9-3.8), 42.6% (38.0-47.4), and 4.3% (2.6-6.6), respectively. In the multivariate model, by increasing the duration of stay (per month) on board, the odds of depression increased by 20% (OR: 1.20 (95% CI: 1.02-1.40)). Also, non-officer seafarers experienced significantly lower psychosocial distress such as anxiety and stress levels than officers. CONCLUSION: High prevalence of depression, anxiety, and general psychiatric disorders among seafarers during COVID-19 was observed. Our findings also highlight the factors that need to be considered to protect seafarers' mental well-being. Further studies to evaluate the impact of COVID-19 on psychological health issues at sea are recommended.