[Purpose] This study analyzed the relationship between fitness and executive functions in adolescents and its influence on academic achievement. [Participants and Methods] The design was cross-sectional. The sample included 713 adolescents (14.2 ± 1.5 years old). Physical fitness was evaluated using flexibility test, strength test, balance test and aerobic test. Executive function was evaluated with the tests (Stroop, Symbol digit, Trail making, Wechsler memory, and MESSY scale). Academic performance was evaluated through the school records. A partial correlational analysis of physical fitness and executive functions with respect to academic achievement was carried out. A multivariate linear regression was performed to identify the physical component model that best defined each of the executive functions. [Results] The analysis showed how academic achievement is significantly influenced, from a physical point of view, by resistance strength (r=0.21), aerobic endurance (r=0.188), and flexibility (r=0.17), whereas from a cognitive point of view it is significantly influenced by inhibition/interference (r=0.25), working memory (r=0.10) and processing speed (r=0.18). [Conclusion] The results indicate that the physical fitness and executive function are closely related and both have a significant influence on academic achievement.