The influence of the principal's transformational and transactional leadership style on teachers' job satisfaction and teachers' performance has been a widely researched topic in many countries. However, there is a dearth of research on this topic in Vietnam. This exploratory study has been conducted in public high schools in the southern region of Vietnam to understand the influence of the transformational and transactional leadership style on teachers' job satisfaction and job performance. This quantitative study used a two-stage cluster sampling method to collect the data from 18 public high schools, which included 144 teachers. The factor analysis and path analysis are used in this study to determine the direct and indirect effects of the principal's leadership on teachers' job satisfaction and teachers' performance. The results show a positive relationship between transformational leadership style and a negative relationship of transactional leadership style on teachers' job satisfaction and performance. The results further indicated that job satisfaction acts as a mediator variable between the principal's leadership style and teachers' performance. The findings of this study would be useful for the Ministry of Education and Training (MOET) and school leaders in Vietnam to bring required changes in the school environment and leadership practices to enhance teachers' job satisfaction and their performance.