These days, academic development is a crucial tool used to build new competencies that result in boosting employee performance. Thus, the research examines the association between staff development and employee performance as mediated by job satisfaction in Dembecha and Machikel districts, in Ethiopia. The researchers used a correlational research design by collecting data from 351 teachers with questionnaires and interviews. Initially, the validity and reliability of scales were checked. As findings, teachers had a high level of staff development, satisfaction, and performance. Moreover, there were no statistically significant differences in teachers' job satisfaction and performance regarding gender, education level, and length of service. There was a positive relationship between staff development, teacher job satisfaction, and performance. Furthermore, job satisfaction partially mediates the relationship between academic development and employee job performance. This study empirically highlighted that to make teachers professionally satisfied and highly performed, various methods of staff development activities should be considered, and the state government should give appropriate inducements to gain new skills that will improve their competencies. This paper also contributes to the theory and literature on teachers' development, job satisfaction, and performance by adding knowledge in the context of Ethiopian situation. This is anticipated to inspire further researchers.