Depression is a growing mental health concern among university students worldwide, including in Thailand. Studies show that between 17 and 40% of Thai university students experience depressive symptoms, although these studies often focus on specific groups and use different measures.

This study aimed to investigate the prevalence and associated factors of depressive disorders among university students across Thailand.

Data were collected with the HAPPINOMETER and the Patient Health Questionnaire-9 scale as part of a nationwide cross-sectional survey. A total of 14 621 students from 33 universities participated in the survey. A series of binary logistic regression analyses were performed to examine the effect of sociodemographic characteristics and health behaviours on the presence of depression.

The results revealed that 31.4% of students experienced depressive symptoms, with 14.2% having major depressive disorder. The students who identified as non-binary had the highest odds of having depression (adjusted odds ratio 2.10, 95% CI 1.7–2.6, P < 0.001). Other specific subgroups were also found to be particularly vulnerable, including women, fourth-year students and those studying in Bangkok, without part-time jobs, living alone and engaging in risky health behaviours like smoking, heavy drinking and poor diet.

The findings underscore the need for comprehensive mental health support and targeted interventions within Thai universities, especially for at-risk subpopulations. Leveraging the existing collaborative networks among Thai universities presents a unique opportunity to mount a coordinated effort in developing and implementing comprehensive mental health strategies tailored to the needs of this vulnerable population.