The study intentions were to examine the correlation and impact of the style of leadership of the principals on job performance of the teachers of secondary school in private sector in Lahore district, Pakistan. It is correlational study in terms of research design. The data was collected from 106 principals and 543 teachers of secondary schools in private sector in Lahore district through adapted instrument. The first tool of the instrument “Principal Leadership Style Questioner (PLSQ) had cronbach alphas of 0.834 for autocratic leadership sub-scale, 0.764 for democratic leadership sub-scale and 0.861 for laissez-faire leadership sub-scale. The Second tool of the instrument “Teacher Job Performance Questioner” (TJPQ) had Cronbach alpha of 0.816. The research question and hypotheses were tested by using percentage, multiple regression, Pearson correlation at the level of p<0.05 significance. The statistics attesting 57.3% variation in teachers’ job performance was due to mutual contribution of principals’ autocratic leadership, democratic leadership and laissez-faire leadership styles. The most commonly employed principals’ leadership style was autocratic leadership in secondary school in private sector in the district. It had statistically significant and strong positive impact on teachers’ performance in the studied area. Whereas reciprocal impact in case of laissez-faire. The principal suggestion was that the school principals should be trained to learn the mixture usage of autocratic and democratic leadership styles wisely in diverse situations and work settings in secondary schools in private sector in the district Lahore, Pakistan.