The ability to make informed decisions is the best approach to success in educational leadership. Unfortunately, college principals find it difficult to take this approach in their colleges including improving teacher educators’ job performance. Several informative studies have been conducted across the globe about what influences teacher educators’ job performance. However, little is known about the influence of transformational leadership style on teacher educators’ job performance. This is also the case in teachers’ colleges in Tanzania. For this reason, this study assessed the influence of transformational leadership style on teacher educators’ job performance in public teachers’ colleges in Tanzania. It specifically explored how transformational leadership style is understood among public teachers’ colleges and investigated the strategies to improve teacher educators’ job performance. The study adopted a mixed research approach and a convergent parallel design. Sixty (60) respondents were involved, they included; teacher educators, principals, deans of students, academic deans and student teachers. Questionnaires, semi-structured interviews and focus group discussions were used to collect data. Data were analyzed through descriptive statistics with the help of SPSS version 20 and thematic analysis. The findings indicated that, the transformational leadership style was noticeable in the meetings and in preparing of the action plan. The principals influenced teacher educators in working with other staff members, giving feedback and supervising student teachers’ works. The study concludes that, principals should adapt transformational leadership style in teachers’ colleges. The ministry of education and college principals should promote professional development programs in order to enhance teacher educators’ job performance. Furthermore, the principals should build a rapport that fosters trust among teacher educators.