This study examined the relationship between parents’ socio-economic status (SES) and students’ academic performance at the Uganda Certificate of Education (UCE) level in selected public secondary schools in Bushenyi District, Uganda. Specifically, the study assessed the effects of parents’ income, educational attainment, and occupational status on academic performance, as well as the moderating role of school support systems. The study was anchored in Bourdieu’s Theory of Social Reproduction (2021), which explains how socio-economic inequalities are reproduced through differential access to cultural and economic capital. A mixed-methods approach was adopted using a cross-sectional survey design. Data were collected from 181 respondents comprising teachers, school administrators, parents, and community leaders through questionnaires, interviews, and document reviews. Quantitative data were analyzed using descriptive statistics, Pearson correlation, and multiple linear regression, while qualitative data were analyzed thematically. The findings revealed a strong positive relationship between parental SES and students’ academic performance. Parents’ income (r = 0.716, p < 0.05), educational attainment (r = 0.751, p < 0.05), and occupational status (r = 0.691, p < 0.05) significantly influenced students’ academic outcomes. School support systems, including counseling and mentoring, moderated this relationship by improving performance among students from lower SES backgrounds, although performance disparities persisted in favor of students from higher SES families. The study concluded that parental SES was a significant determinant of academic performance, but effective school-based support mechanisms could partially reduce SES-related inequalities. The study recommended increased investment in bursaries and school feeding programs, enhanced parental education initiatives, flexible work arrangements for parents, and strengthened school support systems. Further research was recommended to examine longitudinal effects and rural–urban differences.