The COVID-19 pandemic had a huge impact on people's lives due to the fear of getting infected and having the disease, as well as the necessary prevention and containment measures. University students were one of the most affected groups, as they were forced to cope with significant life changes. However, not all displayed symptoms of psychological distress, which means that internal resources such as emotional regulation and resilience may have acted as protective variables. This cross-sectional study aimed to examine the extent to which the relationship between emotion regulation and stress, anxiety, depression, and posttraumatic stress disorder (PTSD) symptoms was mediated by resilience in a sample of university students. Results showed that emotion regulation strategies were positively associated with lower mental health. Some resilience dimensions mediated these relationships, with perception-of-self mediating all associations. Planned future mediated the association between emotion regulation and depression, family cohesion mediated the relation between emotion regulation and stress, and social resources mediated the association of cognitive reappraisal with anxiety and PTSD by suppressing the direct positive relationship. These results highlight the relevance of resilience as a key resource in coping effectively with the uncertainties, and changes that arise during stressful periods such as a pandemic.