To assess the effect of self-efficacy on the relationship between personality and risk-taking in parkour/free-running, a growing high-risk sport.Quantitative cross-sectional study.277 parkour and free-running practitioners were recruited online to complete a survey assessing Big Five personality traits, self-efficacy and perceived risk-taking.Greater reckless risk-taking behaviours were associated with high neuroticism (p = .013) and low conscientiousness (p = .004). Mediation analysis showed that self-efficacy exerted a significant (95% CI) indirect mediation on the relationship between personality traits of neuroticism and conscientiousness, and risk-taking. Extraversion did not predict risk-taking, and was not significantly mediated by self-efficacy.Self-efficacy plays a significant mediation role in the relationship between stable traits of neuroticism and conscientiousness, and risk-taking amongst parkour/free-running practitioners. This may help elucidate reasons underlying risky sports behaviours.