Introduction: Less adherence to antiretroviral treatment (ART) has been found among people suffering from HIV (PWH) with comorbid mental disorders like depression and alcohol use in Mozambique, a Sub-Saharan African country. However, less is explored with regards to other mental disorders. Methods: This study assessed the association of multiple mental disorders and adherence to ART based on the data from primary/tertiary health care facilities in Maputo and Nampula, Mozambique. We administered a sociodemographic questionnaire, Mini International Neuropsychiatric Interview (MINI) Plus 4.0.0 adapted for use in Mozambique to assess mental conditions, and a 3-item self-report to measure ART adherence. Results: Out of 1469 participants, 409 were HIV positive (self-report), with an average age of 36.7 years (SD=9.8), and 30.4% were male. The most common mental disorders were major depressive disorder (27.34%) followed by psychosis (22.03%), suicidal ideation/behavior (15.44%), and alcohol-use disorder (8.35%). Higher levels of non-adherence to ART [(Mean Difference=1.19, 95% CI: 1.04, 1.37)] and the likelihood of missing at least one dose in the last 30 days (OR=3.06, 95% CI: 2.00, 4.67) were found in participants with any mental disorder compared to those without a mental disorder. The highest levels of non-adherence were observed among those with drug use disorders and panic disorder. Conclusions: In Mozambique, PWH with any co-occurring mental conditions had a lower probability of ART adherence. Integrating comprehensive mental health assessment and treatment and ART adherence interventions tailored to PWH with co-occurring mental disorders is necessary to attain optimal ART adherence and reach the UNAIDS ART target. Keywords:Mental disorders, ART adherence, HIV/AIDS treatment, Mozambique