Urban studies have shown that the affordances, constraints and forms of urban climate change mitigation often emerge from ‘entrepreneurial’ modes of governance that have developed in post-Fordist cities. However, comparative research stresses that concepts focused on the growing power of private capital under neoliberalisation are inadequate to comprehend developments in German cities. In this article, we argue that municipally owned corporations occupy critical positions in climate change mitigation governance. While municipal ownership of utilities in principle increases local governance capacities, municipally owned corporations’ roles are shaped by fiscal relations and asymmetric organisational capacities between ‘agents’ and ‘principals’. In the case of Cologne, we show that the city has failed to leverage ownership over its public energy utility to decarbonise energy provision. Managers were able to assert corporate interests in the face of fragmented political actors and entrenched fiscal crisis. In this context of political incapacity and fragmentation, environmental social movements become important actors for translating widely shared decarbonisation objectives into concrete political demands towards municipally owned corporations.