The global development and patient access to Advanced Therapy Medicinal Products (ATMPs)—including gene therapies, cell therapies, and tissue-engineered products—are significantly challenged by divergent regulatory frameworks across major jurisdictions. This thesis conducts a comparative analysis of the ATMP regulatory ecosystems in the United States (US Food and Drug Administration, FDA), the European Union (EU European Medicines Agency, EMA), and Japan (Pharmaceuticals and Medical Devices Agency, PMDA). The primary objective was to systematically map the foundational laws, approval pathways, and evidentiary standards of each framework, analyze their practical impact through integrated case studies, and derive strategic implications for global development. Employing a qualitative, descriptive, and analytical methodology, the research utilized a comparative matrix across six key dimensions: legal foundations, marketing authorization pathways, expedited programs, manufacturing requirements, clinical evidence expectations, and post-marketing pharmacovigilance. Case studies of landmark products, such as tisagenlecleucel (CAR-T) and voretigene neparvovec (gene therapy), provided product-level validation.The analysis identified significant convergence on core scientific principles, including a universal emphasis on rigorous Chemistry, Manufacturing, and Controls (CMC) and long-term safety follow-up. However, critical divergences were found in the legal definitions, the evidence threshold for approval (notably within Japan’s conditional system versus the EU and US models), and the interface with health technology assessment, leading to fragmented global launches and patient access inequities. The conclusion asserts that realizing the full therapeutic potential of ATMPs necessitates a shift towards more adaptive and collaborative global regulation. Recommendations include promoting regulatory reliance, advancing ICH harmonization on CMC topics, and proposing a model for a “Global ATMP Development Passport” to streamline multi-regional submissions. This research contributes to regulatory science by providing a comprehensive tripartite analysis and a roadmap for fostering a more efficient, predictable, and patient-centric international regulatory environment for advanced therapies.