Introduction – Sport and e-sport environments function as performance-oriented spaces where masculine norms emphasizing dominance and success are salient. While these norms influence psychological outcomes, the mechanisms linking them to maladaptive self-regulation require further clarification. This study investigated the associations between masculine norm endorsement, Machiavellianism, and perfectionism, specifically testing the mediating role of Machiavellian traits. Methods – A cross-sectional survey was conducted with 297 adult (65, 9% male, Mage ≈ 24, 4 years) participants, including athletes, e-sport players, and non-athletes. Measures included the Multicultural Masculinity Ideology Scale (MMIS), the Machiavellianism Personality Scale (MPS), and the Short Almost Perfect Scale (SAPS). Data were analyzed using Welch's ANOVA, correlation, and mediation models with 5, 000 bootstrap resamples. Results – Masculine norm endorsement correlated positively with Machiavellianism but showed no direct association with perfectionism. Machiavellianism was positively related to maladaptive perfectionism, and the observed pattern of associations was consistent with an indirect pathway between masculine norm endorsement and maladaptive perfectionism via Machiavellianism (indirect effect: p = 0.013), although no significant total effect was found. No significant indirect effect was observed for adaptive perfectionism. Discussion – Machiavellianism appears to account for the observed association pattern linking masculinity norms to maladaptive perfectionistic self-regulation. In competitive “bastions of masculinity, ” these traits may prioritize strategic success over ethical conduct, highlighting the need for psychological screening to balance high performance with athlete well-being.