Background <p>This study was conducted to reveal the mediating role of athletic character in the relationships among competitive aggression, anger, and sportsmanship in athletes.</p> Methods <p>This research was conducted via a correlational survey model. A total of 852 athletes (mean age = 21.48 ± 4.17) participated in this study, including 343 women and 509 men. The participants competed at amateur and professional levels in various sports, such as team athletes and individual athletes. The participants completed measures of the general information questionnaire, sport character scale, multidimensional sportsmanship orientation scale, and competitive aggressiveness and anger scale. The data were analyzed via the SPSS 25.0, IBM AMOS V25 and PROCESS-Macro statistical programs.</p> Results <p>The study revealed a strong and positive correlation between athletic character and sportsmanship (<i>r</i> = .71, <i>p</i> &lt; .01), whereas competitive aggression and anger were moderately negatively related to both athletic character (<i>r</i> = − .46, <i>p</i> &lt; .01) and sportsmanship (<i>r</i> = − .39, <i>p</i> &lt; .01). The results of the mediation analysis confirmed that the total effect of competitive aggression and anger on sportsmanship was significant and negative (B = -0.425, <i>p</i> &lt; .01). More importantly, the partial mediating role of athletic character was found to be statistically significant (indirect effect: B = -0.337, SE = 0.03, 95% CI [-0.401, -0.278]).</p> Conclusions <p>These findings suggest that strengthening athletic character may mitigate the harmful effects of competitive aggression and anger on sportsmanship.</p>