Professional sport have been developing dynamically in the last few decades. This is evidenced in particular by the growth of its income. The last one is directly related to a quality product produced by a professional sport – a spectacular competition. In particular, in the last few decades, the system of competitions in professional sport has acquired an updated form, significantly changed both quantitative and qualitative indicators of it held. Purpose. To identify key factors in the organizational effectiveness of modern competition systems in professional sports (for example, North American (NFL, NBA, NHL, MLB, MLS), European (UEFA, FIBA / ULEB) and global organizations (ITL/ATP, PGA)). Methods: data analysis and generalization; theoretical interpretation and explanation; analysis of documentary materials, system analysis. Results. Modern systems of professional sports competitions in North America (NFL, NBA, NHL, MLB, MLS) operate according to similar rules. Changes within these systems today are primarily due to public demand. In some leagues (NFL, NHL, MLS,) there has been and continues to be an expansion of teams. In fact, all of these organizations today focus on competitions and in the international sports arena, although until recently the domestic market was more important for them. Due to the development of technology, the leadership of the leagues is increasingly focused on the e-sports market. They develop their own competition systems in a virtual environment and use the latest technologies in conducting and broadcasting real matches, bringing the viewer and the player closer. In Europe, organizations such as UEFA, FIBA/ULEB are also experimenting with changes in the number of teams (increasing in some and decreasing in other competitions) and the format of key tournaments. The professional sports organizations such as ITL/ATP and PGA also impresses with the number of tournaments today. In addition, these organizations are characterized by unique systems of competition, which were also formed as a reaction to external factors (economic, social, informational, etc.). Conclusions. The key factors of organizational efficiency of modern competition systems in professional sports are the level of economic development, technology and information spheres, the level of interest of the international community in kind of sport, the social position of leagues, and most importantly today - development in a pandemic condition.