Purpose: Adolescent obesity is associated with early alterations in lipid metabolism and increased cardiovascular risk. Atherogenic indices such as Castelli Risk Index I (CRI-I), Castelli Risk Index II (CRI-II), Atherogenic Index of Plasma (AIP), and Atherogenic Coefficient (AC) are considered sensitive predictors of cardiovascular disease beyond traditional lipid measures. Therefore, the present study aimed to investigate the effect of 10 weeks of futsal training on selected atherogenic indices in inactive obese adolescent boys. Method: This quasi-experimental study was conducted using a pretest–posttest design with a control group. Thirty inactive obese boys aged 13–17 years were randomly assigned to an experimental group (futsal training, n = 15) and a control group (n = 15). The experimental group participated in a structured 10-week futsal training program, while the control group maintained their usual daily activities. Atherogenic indices were calculated from fasting lipid profiles measured before and after the intervention. Data were analyzed using paired-samples t-tests, independent-samples t-tests, and ANCOVA. Results: Within-group analysis revealed significant reductions in the experimental group for CRI-I (p=0.021), CRI-II (p=0.012), AIP (p=0.011), and AC (p=0.032), whereas no significant changes were observed in the control group (p>0.05). Between-group comparisons at posttest showed significant differences favoring the experimental group for CRI-I (p=0.013), CRI-II (p=0.024), AIP (p=0.041), and AC (p=0.032). These differences remained significant after adjusting for baseline values. Conclusion: Ten weeks of structured futsal training significantly improved atherogenic risk indices in inactive obese adolescent boys. Futsal may therefore serve as an effective, practical, and non-pharmacological strategy to reduce early cardiovascular risk in this population.