Badminton is one of the sports that has witnessed significant development through the great efforts made to expand its spread and to develop it from one level to a better level, relying on the science of biomechanics which studies human movement. Due to the absence of a study that has addressed the biomechanical variables of the long high serve skill in badminton, the researcher decided to address and interpret this study. The importance of the research lies in developing predictive equations for the long high serve skill in badminton based on the biomechanical variables of junior badminton players in order to provide important scientific results for players, coaches, and researchers. The research aims to identify some biomechanical variables of the long high serve skill for junior badminton players, identify the percentage of contribution of some biomechanical variables to the long high serve skill of junior badminton players, and develop predictive equations for the long high serve skill in badminton based on the biomechanical variables of junior badminton players. The researcher adopted the descriptive method using the survey approach on badminton players participating in the 2024–2025 sports season, whose number reached (38) junior players under the age of (16) years. Nine biomechanical variables were measured in addition to the long serve test in badminton. After processing the data, a set of conclusions and recommendations was reached, as the results showed the existence of (9) predictive equations with significant values that can be relied upon in explaining the relationship between biomechanical variables and the skill performance of the long high serve in badminton