Overactive performance monitoring, indexed by greater error-related brain activity, has been frequently observed in individuals with obsessive–compulsive disorder (OCD). Similar alterations have been found in individuals with major depressive and generalized anxiety disorders. The main objective was to extend these findings by investigating performance monitoring in individuals with social anxiety disorder (SAD) and to evaluate the specificity of performance-monitoring changes in OCD. Event-related potentials were used to examine error-related brain activity during a flanker task in 24 individuals with OCD, 24 individuals with SAD, and 24 healthy controls with no history of neurological or psychiatric disorders. Error-related negativity (ERN) and correct-related negativity served as electrophysiological indicators for performance monitoring. Enhanced ERN was expected for both clinical groups, but differential associations with clinical symptoms were explored. ERN amplitudes were larger in individuals with OCD and SAD than in healthy controls. Correlational analyses did not reveal significant associations between ERN and clinical symptomatology in OCD, but a significant correlation with depressive symptoms was found in the SAD group. These findings further strengthen the idea that overactive performance monitoring is independent of clinical symptoms in OCD. Furthermore, it may also represent a transdiagnostic vulnerability indicator, although the relationship with clinical symptoms observed in the SAD group needs additional evaluation.