This thesis provides a comparative analysis of two different governance models in professional sports: UEFA’s federated system and the NBA’s centralized league structure. The objective of this work is to examine how institutional and regulatory frameworks influence financial sustainability, competitive balance and the long-term stability of sports leagues. The research is structured into six chapters. After the introduction and a theoretical framework that reviews literature on governance, the core part of the thesis focuses on two case studies. The first concerns UEFA, examining its multi-level organization, the evolution of regulatory tools such as Financial Fair Play and its transition to the Financial Sustainability Regulations, as well as revenue redistribution mechanisms.