Governments and international organizations are increasingly using public funds to mobilize and leverage private finance for climate projects in the Global South. An important international organization in the effort to mobilize the private sector for financing climate mitigation and adaptation in the Global South is the Green Climate Fund (GCF). The GCF was established under the UNFCCC in 2010 and is the world’s largest dedicated multilateral climate fund. The GCF differs from other intergovernmental institutions through its fund-wide inclusion of the private sector, ranging from project design and financing to project implementation. In this paper, we investigate private sector involvement in the GCF through a qualitative exploratory research approach. We ask two main questions: Do private sector projects deliver on their ambitious goals? What are the tensions, if any, between private sector engagement and other principles of the GCF (most importantly the principles of country ownership, mitigation/adaptation balance, transparency, and civil society participation)? This paper argues that private sector involvement does not provide an easy way out of the financial constraints of public climate financing. We show that the GCF fails to deliver on its ambitious goals in private sector engagement for a number of reasons. First, private sector interest in GCF projects is thus far underwhelming. Second, there are strong tradeoffs between private sector projects and the Global Partnership for Effective Development Co-operation (GPEDC) principles of country ownership, transparency, and civil society participation. Third, private sector involvement is creating a mitigation bias within the GCF portfolio. Fourth, while the private sector portfolio is good at channeling funds to particularly vulnerable countries, it does so mostly through large multi-country projects with weak country ownership. Fifth, there is a danger that private climate financing based on loans and equity might add to the debt burden of developing countries, destabilize financial markets, and further increase dependency on the Global North.