Nigerian public secondary schools are still grappling with the challenge of poor professional teacher performance. While a growing body of research has identified several factors that explain this poor performance, it has not paid much attention to analyzing whether educational leadership is one of the causes and whether it can provide a solution to this challenge. The aim of this study is to investigate the relationship between the leadership behavior of the school principal and the organizational commitment of teachers in high performing secondary schools in the state of Anambra, Nigeria. The study adopted cross-sectional correlational survey design. The population of the study covered of 6,185 teachers in public secondary schools within the Six Education Zones from Anambra State. Stratified, purposive and simple random sampling techniques were adopted in selecting 448 teaching staff from Twenty Eight (28) public secondary schools within the zone. Using the Principal Instruction Management Rating Scale (PIMRS), the sub-dimensions measured the self-perception of school principals with regard to the frequency of leadership behavior in the classroom in daily management, then self-reports were compared with the reports of the teachers in the schools of the school heads. The data were analyzed by descriptive analysis, data transformation and linear regression. The relationship between educational leadership behavior and organizational commitment was analyzed using the Pearson product. The moment of correlation analysis and the extent to which instruction behavior predicts organizational engagement was examined using multiple linear regression analysis. The results demonstrate educational leadership as a positive and significant predictor of professional performance of teachers. These results suggest that improving educational leadership by providing adequate educational resources for teachers and effectively monitoring and supervising them would advance their proficient performance. Accordingly, the study recommends to the management of Nigeria public secondary schools and Anambra State in particular to stock sufficient teaching resources and to ensure that their principals play their instructional supervisory and monitoring roles effectively.