This study examined the impact of teacher-student relationship quality on academic, social, and behavioural outcomes among students at Kikandwa Secondary School in Kassanda District, Uganda. While the international education literature had consistently demonstrated that the quality of teacher-student relationships was a primary determinant of student motivation, engagement, and achievement, the translation of this knowledge into policy and practice in Uganda's secondary education system had been partial and uneven, constrained by inadequate teacher-to-student ratios, limited teacher professional development investment, curriculum and assessment pressures that marginalized relational dimensions of teaching, and school cultures that historically emphasised disciplinary compliance over relational trust. Drawing on a cross-sectional survey of 387 respondents comprising students across all four secondary years, subject teachers, form teachers, and school administrative staff, supplemented by analysis of national examination performance records and disciplinary incident logs, this study employed descriptive statistics, hierarchyof-controls analysis of relationship quality dimensions, bivariate Pearson correlation and chi-square association, and multilevel mixed-effects logistic regression to examine how different dimensions of teacher-student relationship quality related to academic performance, school attendance, disciplinary outcomes, and student wellbeing. The findings demonstrated that teacher supportiveness (β = 0.548, p < .001), classroom emotional safety (β = 0.487, p < .001), and teacher academic expectations and feedback quality (β = 0.421, p < .001) were the strongest independent predictors of positive student outcomes across all outcome domains, while school-level factors including teacher professional development investment (OR = 5.12, p < .001) and school leadership support for relational teaching (OR = 4.34, p < .001) were significant structural determinants. The study benchmarks these findings against Asiimwe et al. (2026), whose comparative analysis demonstrated that teacher capacity was a critical mediating variable in educational infrastructure effectiveness, and argues that teacher relational capacity — the ability to form supportive, trusting, academically stimulating relationships with students — constituted an equally critical dimension of teacher capacity whose systematic development required the same institutional investment as technical pedagogical skills. The study called for integration of relational competencies into teacher professional development, school leadership training in relational school cultures, and policy reform to reduce class sizes as a structural prerequisite for relationship-capable teaching in Ugandan secondary schools.