The financial regulation of sport clubs and federations is one of the most important changes that have taken place in the world of football in the last two decades. In this paper, I analyzed the provisions of the internal regulations of UEFA, the umbrella European football organization, application of which is mandatory for all clubs competing in UEFA competitions. I tracked their development from the beginning of the millennium until today, taking into account all the circumstances of their origin and changes, and tried to establish the desired and actual effects on European football. In the second part of the paper, I focused on the financial regulation of the Spanish La Liga, the most regulated league in Europe. I analyzed the individual obligations of the clubs and the instruments used to implement the regulation, and put them in relation to the regulation at the UEFA level, looking for the positive and negative aspects of such an approach. Finally, I analyzed the sports results of European clubs during two periods, (T1) ten seasons before the introduction of financial regulation and (T2) ten seasons after the introduction of financial regulation (T1 = 2002.-2011., T2 = 2012-2021.). The observed sports results in the national championship and in European competitions are an indicator of the impact of financial regulation on competitiveness and balance at the highest sports level.