The positive effects of physical activity on physical fitness, bone health, academic achievement, cognitive functions, mental health, and reduced obesity have been proven. This study aims to investigate the relationship between sports club activities, physical activity selected health-related fitness, and the d2 attention test. A cross-sectional study was conducted in different sports clubs. A total of 78 male students aged 10-13 years participating in various branches of sports clubs were included in the study, 42 of whom were assigned to the sports group and 36 to the control group. Questionnaires were administered to assess sports club participation and attention levels, while physical health profiles were tested with body composition and Yo-Yo IR1C performance measures. Data were analyzed according to sports participation and the five most frequently reported sports. The means and standard deviation of each study value were calculated for the total subjects and by participating in sports activity using the IBM SPSS (version 23) analysis program. Data normality was checked and confirmed by the Skewness and Kurtosis Tests. The results showed that boys enrolled in a sports activity had lower body mass (-17.9%, P < 0.05 d = 0.72), body mass index (-13.4%, P < 0.05, d = 0.87), and body fat (%) (-54.1%, P < 0.05, d = 1.38) and higher VO2max 32.3% (P < 0.05, d = 3.67), than the non-active group. The boys active in sports clubs also had better results in the total number of items processed (11%, P < 0.05 d = 0.50) and in concentration performance (17.7%, P < 0.05 d = 0.56) than the non-active group. In correlation analyses, VO2max was negatively associated with body mass, body mass index, and body fat (P = 0.011; P = 0.001 and P = 0.00, respectively) and positively related to the total number of items processed and concentration performance (P = 0.003 and P = 0.015, respectively). In the Pearson Correlation analyses, body fat showed a lower negative correlation with TN (r = 0.33; P = 0.003) and CP (r = 0.28; P = 0.015). Boys participating in regular sports have lower body mass, BMI, and BF values. In addition, boys who participated in sports showed higher imaginary fitness and selective attention and concentration capacity results, as expected, for any sports part compared to their body peers. Another attempt from this study is that body mass and body fat percentage recovery are negatively associated with fitness. Considering the increasing prevalence of obesity in children and adolescents due to sedentary living, which has become a worldwide epidemic, it is recommended that pedagogical and public health strategies and policies be developed based on the physical fitness level of children.