This study examined whether and how moral judgment components (moral reasoning and moral value evaluation) combined with self-serving cognitive distortions are related to peer bullying (including associated participant roles) among adolescents. A total of 522 adolescents (49% males) from grades 1 to 4 of three public secondary schools in Spain (M[subscript age] = 14.6 years, range 12-18 years) completed questionnaires on moral judgment, self-serving cognitive distortions, and bullying. Bullies and bully-victims showed the lowest levels of moral judgment and the highest levels of self-serving cognitive distortions. In contrast, moral judgment was highest and self-serving cognitive distortions lowest for defenders and bystanders. Self-serving cognitive distortions mediated completely the relationship between moral reasoning and bullying, and partially between moral evaluation and bullying. Multigroup analyses indicated that the strength of the relationships between the moral judgment components and self-serving cognitive distortions varied across adolescents' role. Anti-bullying intervention programs should include the facilitation of moral reasoning and valuing as well as the reduction of self-serving cognitive distortions.