Abstract: Employing a scoping review method, this study systematically explores the impacts of youth early sport specialization on adolescents’ physical and mental health as well as athletic performance. This paper further identifies the prevalent global predicaments of youth early sport specialization and proposes context-specific strategic countermeasures tailored to China’s youth sports governance. The findings reveal that youth early single-sport specialization commonly leads to overuse injuries, athletic burnout, and truncated athletic careers, which adversely affect adolescents’ physical and mental wellbeing and constrain their long-term athletic development. Although specialized training contributes to improved athletic competence, such benefits are contingent upon multiple moderating factors, including sport modalities and training structure arrangements. A tri-dimensional analysis at macro, meso, and micro levels illustrates the core incentives for the increasingly younger onset of sport specialization. At the macro level, excessive emphasis on competitive achievements, prevalent social biases, and the commercialization of the youth sports training industry misguide the developmental orientation of adolescent sports training. At the meso level, study-training contradictions and outdated talent cultivation concepts form structural institutional obstacles. At the micro level, traditional family perceptions and adolescents’ maladaptive psychological status further accelerate premature specialization. These multi-level factors jointly undermine adolescent athletes’ physical and mental health and impede their sustainable athletic development. Targeting the above issues, this study establishes a systematic framework for early adolescent sport specialization in China. Specifically, diverse developmental goals should be formulated to consolidate the physical and mental foundation of young athletes. Scientific design and standardized management of training practices are required to conform to adolescents’ physiological and psychological growth patterns. Furthermore, a comprehensive social support system should be constructed to facilitate the sustainable and healthy athletic development of adolescent athletes.