The goals of this study were to investigate technical and vocational education (TVET) teachers' progress in their knowledge, perceptions, and competencies related to Industry 4.0 components and Science, Technology, Engineering, and Mathematics (STEM) within the context of a professional development program. A case study design was followed to reveal in-depth information on teacher improvement. Data sources included the "Teacher Knowledge Survey, Teacher Perceptions Survey, and Industry 4.0 and STEM Competencies Survey." Results indicated significant improvement in teachers' Industry 4.0 competencies and their content knowledge of Industry 4.0 components and STEM. Teachers reported a culture of collaboration in their school, increased teacher and student motivation, and positive attitudes toward TVET with implementation of the STEM PD program. The results point to the need to help teachers in designing certain aspects of STEM lesson plans including the integration of mobile programming, robotic programming and virtual reality meaningfully into the lesson content. Further implications for research and practice are presented in light of the findings.