Notwithstanding the large consensus on the idea that justice should be favoured in school contexts to promote student well-being, there is still a lack of research that has investigated how the experience of justice at school spreads impact on global adolescent psychological health. The aim of this study is to investigate the degree to which the experience of teacher (in)justice is possibly related to some of the indicators of adolescent global psychological health, namely individual and social functioning, psychological problems, and somatic symptoms. We also test the role of two components of school-specific well-being, i.e., emotional engagement and classroom connectedness, here considered as potential mediators between teacher justice and psychological health. Structural equation modelling indicated that teacher justice is positively associated with emotional engagement, classroom connectedness and individual functioning, and negatively related to psychological problems. The relation from teacher justice to individual functioning was partially mediated by emotional engagement and classroom connectedness. The relation from teacher justice to social functioning and somatic symptoms was fully mediated by classroom connectedness, while a partial mediation was found between teacher justice and psychological problems via classroom connectedness. These results are commented at the light of their implications for teacher practices.