AbstractObjectiveCharacterized by setting high standards for performance, perfectionism is a transdiagnostic process implicated in the development and maintenance of psychopathology. In contrast, cognitive flexibility is associated with enhanced mental health. Yet, the relationship between perfectionism and cognitive flexibility is understudied. We examined the relationship between perfectionism and cognitive flexibility, and whether emotion regulation strategies moderated the association between them.MethodAdult participants (N = 486) were recruited online and completed questionnaires on perfectionism, emotion regulation and cognitive flexibility.ResultsPerfectionism negatively correlated with one of the two aspects of cognitive flexibility assessed. Reappraisal, but not suppression, moderated the relationship between perfectionism and flexibility.ConclusionsResults indicate that perfectionism is associated with inflexible appraisal of everyday challenges. Additionally, cognitive reappraisal attenuates the negative relationship between perfectionism and cognitive flexibility; except in individuals with high narcissistic perfectionism for whom the debilitating relationship between the two variables is enhanced by reappraisal.