This large-scale quantitative study investigated how secondary school teachers’ classroom management practices relate to multiple dimensions of student engagement. Using data from 26,849 students across 401 classrooms in 54 US high schools, and applying three-level hierarchical linear modelling, the study found that teachers’ use of positive behaviour supports (e.g., prompting, recognising appropriate behaviour) was significantly and positively associated with students’ active classroom engagement. Punitive or reactive management practices, by contrast, were associated with lower engagement and poorer school climate perceptions. The study draws on both motivational-developmental and ecological frameworks of engagement, measuring behavioural and affective dimensions including student-teacher connectedness, student-peer connectedness, whole-school connectedness, and active in-class engagement. The findings have direct implications for teacher training and professional development focused on proactive classroom management in secondary settings.