Globalization, uncertainty arising from the development of science and technology, competition and changes in needs affect not only for-profit organizations but also schools that provide education services. In this challenging position schools are expected to be effective; school principals are expected to own agile leadership characteristics. The aim of the research was to predict whether the agile leadership characteristics of school principals perceived by teachers affect school effectiveness. The research was carried out in relational survey model. In the study, data were collected from 605 teachers working in public / state schools in Istanbul in the 2020-2021 academic year, with the help of School Effectiveness Index and Marmara Agile Leadership Scale. According to the prominent findings, while the agile leadership characteristics of the school principals do not make a significant difference according to the gender, education level, seniority and age of the teachers, according to the school levels they create a significant difference. While school effectiveness perceptions of teachers’ do not show a significant difference according to their gender and education level; It has been determined that there are significant differences according to the school levels, ages and seniority of the teachers. Finally, the agile leadership characteristics of school principals perceived by teachers positively and importantly predict school effectiveness.