Background: The school is one of the most salient developmental contexts for children. However, little is known about the associations linking the school environment to child adjustment in a non-Western context, not to mention the potential processes that may mediate these associations. Aims: This study examined the associations of school- and classroom-level characteristics with child adjustment and tested whether these associations were mediated by teacher-child relationship qualities. Sample: Cross-sectional data were collected on a representative sample of 1777 children (mean age = 55.14 months; 50% of them were girls) from 100 kindergartens in Hong Kong, China. Methods: Using self-reported questionnaires, teachers rated their school-level environments, their classroom chaos, their closeness and conflict with children and children's socioemotional competence and academic ability. Meanwhile, parents rated children's behavioural problems. Results: Multilevel structural equation modelling revealed that the school-level environment and classroom chaos were uniquely associated with children's socioemotional, behavioural and academic adjustment. Moreover, the associations of the school-level environment and classroom chaos with child socioemotional and academic adjustment were mediated by teacher-child closeness and conflict, whereas the associations of the school-level environment and classroom chaos with child behavioural problems were mediated by teacher-child conflict only. Conclusions: Findings indicated how school- and classroom-level characteristics may be uniquely associated with child adjustment and how teacher-child relationships may be implicated in the underlying mechanism, highlighting the potential utility of targeting school- and classroom-level environments and teacher-child relationships in promoting child development.