The study results revealed no statistically significant difference in teachers' perceptions of principals' technological leadership and school effectiveness in terms of teachers' gender, seniority, branch, working time at the current school, technological competence, and daily technology use. However, the findings showed a significant difference in the perceptions of technological leadership by age but not in the perceptions of school effectiveness. The analysis results revealed a strong or very strong correlation between the technological leadership and its sub-dimensions and the school effectiveness sub-dimensions. It was found that a positive increase in any sub-dimension of the technological leadership scale improved school effectiveness, and there was a significantly positive and very high relationship between school effectiveness and technological leadership. As technological leadership increased, so did school effectiveness. Accordingly, technological leadership explained 50.8% of the change in school effectiveness. Principals' technological leadership, mediated by teachers' technological literacy, affected teaching and school effectiveness.