Public procurement for green innovation refers to tailoring public procurement policies in such a way as to promote green innovation within the wider economy. This study considers the nature of these policies, their legal limits, best practices, and how they have been implemented across a sample of four different OECD countries. The study begins with a general consideration of public procurement for green innovation and its component parts (i.e. green public procurement and innovative public procurement). This includes the theory behind such measure, their limitations, and a comparison with other ways in which a government may promote green innovation. Also included in this study is an analysis of the legal framework of public procurement for green innovation, involving such agreements as the General Procurement Agreement (GPA), the Agreement on Subsidies and Countervailing Measures (SCM), the General Agreement on Trade in Services (GATS), and various regional trading agreements (RTAs). This analysis suggests that the legal questions surrounding any given policy will turn upon its unique legal framework (i.e. the agreements to which the country in question is a signatory). Where a policy falls under the GPA there is flexibility to pursue green innovation, while the SCM appears more restrictive. RTAs incorporating public procurement provisions are quite heterogeneous, depending generally on whether the parties to the RTA are also Parties to the WTO GPA. Finally, an analysis of four sample countries indicates that, at present, public procurement for green innovation is not being widely or systematically pursued. A range of unique, individual policies does exist, and demonstrates that each country has been able to tailor its approach to their perceived needs.