This study investigated a moderated mediation model to elucidate specific mechanisms underlying state anger among undergraduate students during the COVID-19 pandemic. The model proposed that the relationship between intolerance of uncertainty and state anger would be mediated by perceived COVID-19-related stress and moderated by levels of social trust. A sample of 318 undergraduate students completed self-report questionnaires, and data were analyzed using the Process macro. Results indicated that intolerance of uncertainty had both a direct positive association with state anger and an indirect positive effect through elevated perceived COVID-19 stress. Notably, this mediating effect diminished with higher levels of social trust. These findings suggest that fostering individual traits, such as tolerance for uncertainty and effective stress regulation, along with enhancing social trust, may be critical to reducing state anger among students during pandemic conditions.