The purpose of the study was to elucidate the relationship between personality traits, perfectionism, and mental health (self-efficacy, positive emotions) among competition riders. Data were collected by online questionnaires among 662 licensed competition riders in Norway. The results showed that riders who were high on conscientiousness and low on neuroticism had better mental health than other riders. Self-oriented perfectionism predicted mental health and mediated partly the associations between personality traits and mental health. Socially prescribed perfectionism had no association with mental health. The findings indicate that self-oriented perfectionism may have a positive effect on the mental health of the riders. The high degree of conscientiousness that many of the competition riders possess may be associated with self-oriented perfectionism and positive outcomes.