Transformational leadership is a leadership style that prioritizes commitment values, patterns, and performance to achieve organizational goals needed in the 21st century. This leadership style is widely applied in developing countries and has the best educational status in the world, such as in Finland and the United States. Researchers have recommended that transformational leadership is an important aspect of teacher performance; however, whether the effect varies across related studies and the robustness of the overall effect size remains unclear. A meta-analysis technique was used to synthesize the results from 65 independent studies and investigate the overall relationship between transformational school leadership and the three measures of teacher performance. This study found that, in terms of the average influence measure, transformational school leadership positively influenced teacher job satisfaction, commitment, and self-efficacy.