(1) Background: This article aims to answer the question of whether the Republic of Poland, by stipulating in the Constitution of 1997 the principle of sustainable development and ecological security, has created favourable conditions for the development of renewable energy. (2) Methods: The research is conducted using descriptive methods and—due to the legal nature of the publication and the crucial role played by the dogmatic method—it consists of the interpretation of legal acts and court decisions. (3) Results: Over the last few years, state authorities have introduced a number of regulatory and legal mechanisms to increase the stability of the operation of renewable energy sources, including the development of biomass or geothermal energy, as well as the development of energy clusters and cooperatives. This article characterises specific solutions and assesses their effectiveness. (4) Conclusions: The state authorities should take further specific actions aimed at achieving the sustainable development of the renewable energy sector in Poland. These actions should be primarily aimed at the use of huge resources of renewable energy sources, saving the consumption of energy resources, reducing the demand for final energy, gradually converting electricity production from coal to renewable energy sources (RES), and moving away from fossil fuels for heat production in favour of RES.