Transnational municipal networks (TMNs) have been heralded as actors that can avert a climate catastrophe by filling the “emission gaps” left by national climate policies. But can these networks reduce the carbon pollution of power plants, the world’s largest sites of climate-disrupting emissions? Using an international data source on individual power plants, we empirically analyze this issue. Findings reveal that after accounting for their structural properties and the national policies to which they are subject, power plants emit less CO2 when nested in cities that are members of TMNs and this is especially true of plants in less developed countries. In contrast, national climate policies are unrelated to plants’ environmental performance over time. Although our analyses suggest TMNs help to reduce the emissions of the typical power plant, they also indicate they have little bearing on the emissions of the world’s most egregious polluting plants.