We investigated (1) grade differences in perceived stigma-based peer victimization (SBPV); (2) differences in perceived student and teacher/staff defending against types of SBPV; and (3) whether defending against SBPV affected student subjective wellbeing (SSWB) via anti-victimization school climate perceptions. Participants were 1124 US adolescents (48% girls, 48% boys, 3% another identity) in Grades 6-9. Participants identified as Hispanic (61%), Black (12%), White/Non-Hispanic (12%), and other racial/ethnic identities (15%). We found small differences in perceived defending against different types of SBPV. There were no differences between grades for perceived student defending, but teachers/staff defended 9th-graders less than 6th-graders across all types of SBPV. Student defending against ability-based victimization and teacher/staff defending against sexuality- and weight-based victimization predicted SSWB indirectly through anti-victimization school climate perceptions. Although SBPV is harmful to adolescents' school functioning, students and teachers/staff can defend against SBPV to promote more adaptive perceptions of school climate and wellbeing.