The present research (N = 169) examined the relationship between narcissism and anger responses considering the moderating role of social exclusion and the mediating role of hostile attribution bias. For this, social exclusion scenario and inclusion scenarios were utilized, and a total 183 participants were recruited from the UK using the online platform Qualtrics. Fourteen responders were excluded for failing the attention check question and the remaining 169 participants were randomly assigned to either the social inclusion condition (n = 87) or the social exclusion condition (n = 82). The results demonstrated that participants with high narcissism reported a greater level of anger when socially excluded, yet not when they were socially accepted. Furthermore, we observed indirect (mediation) effects in which greater levels of anger were affected by higher narcissism via higher levels of hostile attribution bias in both social exclusion and inclusion conditions, but the indirect effect was stronger in the condition of social exclusion than in the condition of social inclusion. Thus, the strong direct and indirect relationship between narcissism and anger can be found in the social exclusion condition, while the weaker but significant indirect relationship between narcissism and anger via hostile attribution can be also observed in the social inclusion condition. We discuss the implications of these findings and future research directions.