This study aimed to evaluate the effectiveness of a training program based on the kinetic chain concept and the angular kinetic energy index in improving the biomechanical variables of the tennis serve among young players in Iraq. The research adopted a quasi-experimental approach using a one-group design with pre- and post-tests. The sample consisted of 12 young players (aged 16–20 years), intentionally selected from tennis clubs in Baghdad and Basra. Participants underwent a specialized training program for eight weeks, and biomechanical variables were measured using three-dimensional motion analysis devices and high-speed cameras before and after the program. The results revealed statistically significant differences (α ≤ 0.05) between the pre-test and post-test measurements. A substantial improvement was observed in the mean serve speed (from 95 km/h to 117 km/h) and serve accuracy (from 65% to 85%). The findings also indicated a significant enhancement in angular kinetic energy indices and motor coordination efficiency according to the kinetic chain model. The study demonstrated that specialized biomechanical training effectively enhances serve performance among young players. The study recommends that coaches and training academies adopt this training approach to improve performance and reduce injury risk, while emphasizing the need for further research on larger and more diverse samples.