In this technological era educational institutions, facing many challenges to improve the performance of the institutions through successful leadership behaviors. The effective leaders play an essential and important role in achieving the target goals for the betterment of organizations by making subordinates committed and satisfied with their jobs. The aim of this quantitative study is to investigate the relationship amongteachers’ perception of their Principals’ transformational leadership style, teachers’ organizational commitment and teachers’ job satisfaction in public degree colleges Karachi, Pakistan. The aim of this study is to find the role of teachers’ organizational commitment as a mediator between the relationship of Principals’ transformational leadership style and teachers’ job satisfaction as well. The measuring instruments used in the study were Multifactor Leadership Questionnaire (MLQ Form 5X) developed by Bass and Avolio ,Three-Component Model (TCM) survey for organizational commitment developed by Meyer and Allen and Job Satisfaction Survey developed by Spector. Stratified random sampling technique was used to collect the data from 382 college teachers from public sector colleges by survey method. Data were analyzed descriptively by using Statistical Package for the Social Sciences (SPSS) and utilized Structural Equation Modeling technique on higher order constructs to test the hypotheses of the study by using Smart PLS statistical software. The findings of the study revealed that Principals’ transformational leadership style perceived by teachers has a significant impact on teachers’ organizational commitment and teachers’ job satisfaction. The findings of the study also proved that organizational commitment significantly mediates between the relationship of Principals’ transformational leadership and teachers’ job satisfaction. This study contributes empirical evidences for leaders (Principals) to enhance their leadership attitudes to be more efficient and suitable relationship with teachers’ job satisfaction and organizational commitment.