This study aimed to examine the effectiveness of school leadership by exploring the relationships between various school leadership models and practices and different school outcomes, including organizational, teacher, and student outcomes. Data for this study were retrieved from multiple databases, including Web of Science, Scopus, ERIC, Academic Search Ultimate, and TR Dizin-Turkish national index. The analysis synthesized findings from 23 meta-analysis studies, utilizing second-order meta-analysis with the random-effects model. The study revealed a significantly positive relationship between school leadership and school outcomes, with a high level of correlation (mean effect size: 0.46). Additionally, this relationship varied significantly based on the type of school leadership, school outcome, and the quality of the studies conducted.