Justice is at the center of many definitions of character across various lines of research, yet there is little empirical research on how the justice of contexts can foster character virtues. The current study draws from a sample of 1,865 Brazilian fourth and fifth graders across two time points in 60 schools (42.7% White; 48.3% male). A multilevel structural equation model demonstrated the mediating role that justice beliefs play between authoritative school climate and socio-emotional learning, and the character virtues of bravery, fairness, and prosocial leadership even after accounting for grade, gender, ethnicity, and socioeconomic status (SES). This study highlights the importance of understanding the contextual justice of children's environments on the development of character virtues.