Objective: The purpose of this study was to examine the influence of parental responsive support (observed) and perceived parental responsive support on athletes’ self-perceptions and thriving. Methods: Forty-one French-speaking Belgian individual sport athletes aged 12-15 years (M = 13.13, SD = 0.90) and one of their parent’s spent 10 minutes discussing three important athletes’ sport-related goals for the next season. The discussion was video-taped and coded to identify parents’ responsive support behaviors. After the discussion, athletes responded to a series of questionnaires measuring perceived parental responsiveness, self-efficacy, self-esteem, and thriving indicators (i.e., positive affect, vitality, life satisfaction, and health quality). Results: The results show that observed and perceived parental responsive support contributed to athletes’ proximal perceptions of self-efficacy. Both parental observed responsive support and athletes’ perceived parental responsiveness, mediated by athletes’ self-efficacy, were positively related to athlete’s self-esteem. Further, athletes’ perceived parental responsiveness was positively related with thriving while mediated in series by self-efficacy and self-esteem. Conclusion: Overall, it appears that parents’ responsive support (observed) and athletes’ perception of responsive support are associated with positive self-perceptions and optimal wellbeing in young athletes. This study demonstrates that parents can provide responsive support to their children in the sport context. These results add further weight to suggestions that sport organizations should actively include, rather than exclude, parents in their processes.