This study aims to investigate the prevalence and effect of principals' destructive leadership behavior on teachers' organizational commitment in secondary schools within Amhara National Regional State. An explanatory sequential design was employed, combining both quantitative and qualitative research methods. The sample comprised 1257 secondary school teachers and 10 interviewees, selected through multistage stratified and purposive sampling techniques, respectively. Data was collected using questionnaires and semi-structured interviews. Quantitative data analysis involved one-sample t-tests, factorial MANOVA, Pearson correlation, and linear regressions, while qualitative data was analyzed using a narrative approach. The findings indicated a notable prevalence of destructive leadership behavior among principals in Amhara's secondary schools, with laissez-faire leadership being the most common type. The overall commitment level of secondary school teachers was found to be low, but they demonstrated moderate affective commitment, indicating an attachment to their respective schools. Moreover, perceptions of destructive leadership behavior differed among teachers based on gender. The study revealed a significant negative relationship between principals' destructive leadership behavior and teachers' organizational commitment. The findings also demonstrated that there was a negative relationship between all dimensions of principals‘ destructive leadership behavior and each element of teachers‘ organizational commitment. Furthermore, destructive leadership behavior significantly predicted organizational commitment and emerged as a significant predictor overall, explaining 44.4% of the variance in organizational commitment. Among the different elements of DLB, laissez-faire leadership behavior was the strongest predictor of affective, continuance, and normative commitments. Therefore, the study concluded that the decline of teachers‘ OC, which had a return effect on students‘ academic achievement and quality education, was due to the impact of principals‘ DLB. Based on the study findings, it is recommended to provide training for secondary school principals, strengthen follow-up and monitoring mechanisms, build constructive leadership behavior, and elevate the commitment levels of secondary school teachers.