Mental health in young people is a public health challenge worldwide, with around one-fifth of university students suffering from a 12-month mental disorder. In low- and middle-income countries (LMICs) of Southeastern Asia, resources for mental health are limited and counseling services are not regularly established at universities. This review aims to determine the prevalence of mental health problems among university students in 6 ASEAN (Association of Southeast Asian Nations) countries (Cambodia, Laos, Malaysia, Myanmar, Thailand, and Vietnam) and to identify the determinants of mental health. A systematic database search (PubMed, CINAHL, PsycINFO, PubPsych, and Scopus) for peer-reviewed, English language articles, published 2010-2020, reporting prevalence data based on standardized screening instruments resulted in 335 articles; 108 were eligible for full-text analysis, of which 34 could be included in the review. Median point prevalence was 29.4% for depression, 42.4% for anxiety, 16.4% for stress, and 13.9% for disordered eating. Current suicidality was present in 7% to 8% of students. There was a high rate of psychiatric comorbidity. Despite the high prevalence of mental health problems, the willingness to seek professional help was comparatively low. Implications for mental health promotion and prevention in university settings are discussed.