In the international literature, discussion of the impact of physical activities is mainly focused on improvements in quality of life, particularly in terms of health. However, sports can have other positive effects on individuals that may contribute to improving their academic performance. This study explores the effect of physical activities and self-esteem on the academic performance of high school students in central southern Chile, a topic on which there is currently no evidence. A linear cross-sectional regression and probit methods are used to determine the probability of achieving good school performance. However, because there may be selection bias, a Heckman model is estimated in two stages. Individual, academic, family, and socioeconomic factors are taken into consideration. This was done with data obtained from a survey applied to 2,010 high school students. The results provide evidence of the positive impact of physical activities and self-esteem on school performance. However, the effect on academic results increases at diminishing rates. That is, engaging in sports and physical education contributes positively (0.24 to 0.05%), but spending too much time engaging in sports negatively affects school performance (0.89 to 0.1%). While negative self-esteem influences from--5.8% to -2.9%. Therefore, high school students who engage in sports activities and positive self-esteem have better academic performance. Thus, given the implementation of a government policy to increase the hours of physical education, an improvement in academic results could be expected.