Recent studies have highlighted the critical role of mental health in student performance and overall well-being, particularly in South African schools where educational disparities are prevalent. The study employed a mixed-methods approach, including quantitative surveys (n=500) and qualitative interviews (n=30), to gather data from students and teachers in selected schools in four provinces of South Africa. Data were analysed using descriptive statistics and thematic analysis. Findings indicate that mental health programmes led to significant improvements in student self-reported stress levels, anxiety symptoms, and overall academic performance, with a notable increase (25%) in standardised test scores among participating students compared to non-participants. The results suggest that school-based mental health interventions can effectively enhance student wellbeing and academic achievements in South African schools. School administrators should consider implementing or expanding mental health programmes, and policymakers could prioritise funding for these initiatives within the educational budget.