This study aims to analyze the influence of transformational leadership, organizational culture, and the managerial role of the principal on teacher performance in private junior high schools in Bojongsari District, Depok City. This research employed a quantitative approach using a survey method with a sample of 139 teachers selected through proportional random sampling. Data were collected, questionnaires that had been tested for validity and reliability, and analyzed using partial correlation, multiple correlation, and multiple linear regression techniques. The results show that transformational leadership has a positive and significant relationship with teacher performance (r = 0.613; p < 0.001), but becomes insignificant after controlling for other variables. Organizational culture also has a positive and significant relationship with teacher performance (r = 0.669; p < 0.001), although its effect weakens when controlled by the managerial role of the principal. Meanwhile, the managerial role of the principal shows the strongest and most significant relationship with teacher performance (r = 0.899; p < 0.001), and remains significant even after controlling for other variables. Simultaneously, transformational leadership, organizational culture, and the managerial role of the principal have a very strong relationship with teacher performance (r = 0.903). In conclusion, the managerial role of the principal is the most dominant factor in improving teacher performance, followed by organizational culture and transformational leadership. Therefore, optimizing the principal’s managerial role should be prioritized to enhance teacher performance.