Pathological narcissism (PN) is a common psychopathological issue leading to maladaptive strategies to cope with self‐esteem threats, including self‐enhancement and exploitation (grandiose strategies) or internalized shame, depression, and social withdrawal (vulnerable strategies). Mentalizing is a key process for regulating self and other representations and their associated emotions. Patients with PN further struggle with emotion dysregulation (ED), which during development is intertwined with the growing capacity to mentalize. We seek to contribute to emerging empirical data documenting the associations between PN and ED and between PN and mentalizing, and to provide information on the nature of their mutual relationships. In the present study, we assessed PN, ED, and three mentalizing dimensions (mentalizing self, other, and motivation to mentalize) in 183 patients consulting in our outpatient unit specialized in ED. We found that narcissistic vulnerability was negatively associated with self‐mentalizing and positively associated with overall ED, both even after adjustment for borderline and attention deficit hyperactivity disorder (ADHD) symptoms. However, the association with ED was not maintained after further adjustment for self‐mentalizing or overall‐mentalizing, which suggests that mentalizing may play a mediating role in this relationship. On the other hand, narcissistic grandiosity was positively associated with other‐mentalizing and ED and negatively associated with self‐mentalizing in bivariate analyses, but these last two associations were not maintained after adjustment for comorbid borderline and/or ADHD symptomatology. This study provides new information on the link between PN and ED and on key mentalizing dimensions meaningfully relating to PN, notably through a potential role of self‐mentalizing processes between PN and ED.