A number of school-based mental health prevention programs have been found to be effective in research trials, but little is known about how to support implementation in real-life settings. To address this translational problem, this systematic review aims to identify effective strategies for enhancing the implementation of mental health prevention programs for children in schools. Four electronic databases were searched for empirical, peer-reviewed articles in English from January 2000 to October 2021 reporting the effects of implementation strategies for school-based universal mental health programs. Twenty-one articles were included in the narrative synthesis and assessed for quality using the Mixed Methods Appraisal Tool. Twenty-two strategies were found to be effective at improving program fidelity or adoption. The strategies with the strongest positive evidence base were those that involved monitoring and provision of feedback, engaging principals as program leaders, improving teachers' buy-in and organising school personnel implementation meetings. We recommend school-based practitioners trial strategies with positive findings from this review as part of their continuous quality improvement. This review highlights the pressing need for large-scale, randomised controlled trials to develop and trial more robust strategies to enhance adoption, as the five implementation studies found to measure adoption used qualitative methods limited by small samples sizes and case study designs.