The purpose of the article is to consider, using the example of the EU and Russia, potential challenges and problems of legislative regulation of green finance in the framework of the implementation of the current sustainable development agenda. Using the method of political and legal analysis, the study analyzes the current state of legal regulation and political initiatives of the Russian Federation and the EU in the field of green finance. Initially, the paper considers the legal institutionalization of green finance in the field of financial legal relations, and certain legal aspects related to environmental taxes within the framework of the green finance system. Further the work moves on to a review and analysis of EU and Russian policy along with legal and regulatory aspects in the field of green finance. The research gives reason to say that both Russia and the EU are characterized by the lack of unified definitions within the framework of green investments, which creates additional obstacles for potential investors. Of particular importance for the development of the green finance sector is the development of systems and standards for assessing the impact of green finance on the achievement of environmental goals. However, there is currently no legal institutionalization of such standards, which takes the issue beyond the scope of direct legal regulation. Russia, in order to join the global process as a full participant, needs to work out a number of issues of a legal and organizational nature, including issues of the legal nature and system of environmental payments, their administration, in particular determining the procedure for interaction with external verifiers in the framework of the green projects implementation. The lack of political motivation inhibits initiatives in the sphere, while the issues of legal regulation often undeservedly remain in the shadows. This, in turn, causes a theoretical gap, which this work intends to fill. In order to ensure sustainable development, the possibilities of international regulatory cooperation and the harmonization of legislation are becoming important. From a practical point of view, the study is of interest to both lawyers and specialists in the field of financing and investment.