The International Olympic Committee and FIFA, as International Sports Organisations (ISOs), determine which country or city will host mega-sporting events, and according to which conditions. By including green policy requirements in the criteria to be met by candidate countries and cities, ISOs have in recent years started to play a leading role in climate change ‘glocal’ governance. The aim of this article is to examine the conventional and unconventional legal tools that ISOs have developed and implemented in order to reduce the carbon footprint of the World Cup and the Olympics. As this analysis will hopefully make clear, the regulatory framework of mega-sporting events bidding holds a distinctive and important place in the context of climate change law and governance.