Alexithymia is a personality construct characterized by difficulties in identifying and describing emotions. Previous research has identified a positive association between alexithymia and aggression, and impulsivity may account for some of that association. This study tested a path model of associations between alexithymia, five facets of impulsivity (negative urgency, positive urgency, lack of premeditation, lack of perseverance, and sensation seeking), and verbal and physical aggression in a sample of 503 undergraduate students. Alexithymia had significant positive associations with all facets of impulsivity except for sensation seeking. Negative urgency and (lack of) premeditation mediated the relationship between alexithymia and verbal aggression. Positive urgency, negative urgency, and (lack of) premeditation mediated the relationship between alexithymia and physical aggression. Positive urgency also moderated the relationship between alexithymia and both forms of aggression, increasing the strength of those associations. These results highlight the role of emotion dysregulation in the context of aggression and support the use emotion regulation skills training in anger and aggression management programs.