Psychological flexibility skills (PFS) have shown to be an important aspect of wellbeing among the general population, however, there is a gap in research exploring flexibility skills among athletes. The present study examined the effects of PFS on young athletes’ (n = 106, M = 19.9) psychological wellbeing, symptomatology, and gender differences. Data was investigated using correlations and linear regression analyses. Higher PFS was associated with subjective wellbeing, recovery experiences, self-esteem, and lower levels of perceived stress, and depression symptoms (r = 0.30-0.53). Among the PFS, value-based actions acted as the strongest predictor for mental wellbeing and symptoms. In addition, avoidance of distressing thoughts and emotions related to sport was a significant predictor for self-esteem, symptoms of stress and depression but not for subjective wellbeing and recovery experience. Also, our results highlighted gender disparities, with female athletes reporting higher stress and depressive symptoms, while males exhibited better mental wellbeing, psychological recovery, self-esteem, and higher psychological flexibility skills. Overall, engagement in value-based actions may enhance athletes’ mental wellbeing. Further, it might be important to pay attention to individual differences related to gender both when assessing psychological flexibility skills and when applying interventions aimed at enhancing mental wellbeing among athletes.