The United Nations Intergovernmental Panel on Climate Change (IPCC) has called for private sector participation in global carbon governance and corporations now seem to be heeding the call at an unprecedented scale. Both critics and proponents of corporate social responsibility (CSR) interpret this as a necessary but uncertain development. Business response has demonstrably failed in the past. Contributing to the CSR and private environmental governance effectiveness literature, this article argues that while voluntary corporate climate governance efforts are essential and improving, they are far from sufficient for meaningful decarbonization. Through an evaluation of the three main underlying corporate carbon management practices (target setting, carbon pricing and carbon reporting), the article highlights how company efforts create business advantage (e.g. risk management) but fall short on ecological effectiveness (i.e. absolute carbon reduction). In response, the paper argues the importance of greater climate policy co‐regulation. This includes indirect enabling by governments and the IPCC to encourage incremental improvements in company efforts. It also includes more direct, state‐led prescriptive interventions coordinated across supply chains and supported by international organizations, to ensure corporate participation and deeper transformative change to business models, industry structures and consumptive patterns at the root of the global climate crisis.