Abstract The COVID-19 pandemic exerted a tremendous toll on individuals’ mental health. This study aimed to examine the associations between men’s common mental disorders (CMD), intolerance of uncertainty (IU), and social support (SS). A cross-sectional online study was carried out in all Brazilian states. Participants were 1.006 adult men recruited through social media using a snowball technique. Men completed the Self-Report Questionnaire-20, the Intolerance of Uncertainty Scale, the Two-Way Social Support Scale, and a sociodemographic questionnaire. In addition, a t-Test and a regression analysis were performed. Men in the clinical group reported significantly higher levels of IU and lower levels of SS. Furthermore, SS moderated the relationship between IU and CMD, suggesting that SS might help protect men’s mental health against the deleterious effects of IU in a pandemic scenario. These results indicate that different forms of social support seem to be a promising focus of psychosocial intervention in this context.