This study aimed to determine the level of transformational leadership practices by school principals in the national secondary schools in the state of Pulau Pinang, Malaysia. The four dimensions of transformational leadership studied were vision identification, modeling, goal acceptance and individual support. The study also looks at the level of organizational health as well as the relationship with the practice of transformational leadership by the national secondary school principals’. The respondents consisted of 226 teachers employed in 16 national secondary schools in the state of Pulau Pinang, Malaysia. The data obtained was analyzed using SPSS version 20.0. Descriptive analysis and inferential analysis were used to analyze the influence of the relationship. The study found that school culture functions as a moderator in the relationship between the transformational leadership style of school principals’ and the organizational health of the secondary school teachers’ in the state of Pulau Pinang, Malaysia. In addition, school culture as a moderator in the relationship between transformational leadership and organizational health is a new discovery in the field of leadership. This is because the organizational health of secondary schools has never been investigated by local researchers. Most previous studies have highlighted transformational leadership and school culture has a direct influence on school improvement.