From wind turbines and renewable energy landscapes to environmental talks at the UN summits in Copenhagen (2009) and Cancún (2010), there is growing interest in the links between business and the environment. Much geographical work has critically focused on state-environment links, while economic geographers have attempted to theorize the emergence of markets and economies, in part through understanding the economy through a relational, cultural lens. However, while there has been significant work on critical approaches to the environment and capitalism, there has been a lack in explicit focus on the firm and its role, firstly, in mediating economic-environmental relations, and secondly in the production of specific environmental outcomes. Drawing on literatures on cultural political economy (CPE), Science and Technology Studies (STS), Actor Network Theory (ANT) and political ecology, the paper argues for a reincorporation of the firm into critical work on the environment in geography, and proposes three ways in which the firm can be usefully theorized in such work: as a relational economic and cultural actor, as a sociotechnical mediator, and as the producer of hybrid socionatures.