The study aimed at staff professional development and its impact on students’ academic performance among secondary schools in Kanungu district. To accurately examine the relationships between professional development models, teaching practices, and student achievement in Kanungu District secondary schools, a mixed-methods research design was employed over three academic years from 2017-2020. First, a quantitative approach was utilized to explore longitudinal correlations. Records of in-service training provided to teachers between 2015-2018 at 17 randomly selected schools were analyzed to categorize varying attributes of each program based on indicators established in previous studies as impacting effectiveness, including duration, content focus, pedagogical approach, funding source, and continuity. From the findings, the correlation between Employee Engagement and Students' Academic Performance was 0.766. This positive correlation suggested that as Employee Engagement increases, there was a positive linear relationship with students' academic performance. The p-value associated with the correlation coefficient was 0.000 (less than 0.01), indicating that the correlation was statistically significant at the 0.01 level. This strengthens the evidence that there was a significant relationship between Employee Engagement and Students' Academic Performance. Based on the emergent evidence, it is recommended that the district education office establish a periodic cadre of lead subject teachers to conduct regular school visits for modeling, co-planning, and non-evaluative feedback cycles as part of departmental improvement plans