The article highlights the process of reforming local self-government and territorial organization which took place in Ukraine in 2014–2020 and which led to a radical change in the model of public power at the local level. Accordingly, the purpose of the article is to provide a comprehensive analysis of the local self-government (decentralization) reform in Ukraine, outline the problematic aspects that need to be addressed for its successful completion, and discuss the impact of the Polish decentralization experience on the reform. The timeframe of the study covers 1970-2023. The author analyzes the socio-political preconditions for the reform, its positive results, and the main challenges faced by the decentralization process. The main objective of the reform was to form an original national model of local self-government with successfully functioning territorial communities. In general, this objective has been accomplished since, even in the context of the Russian-Ukrainian war, such communities show their efficiency and cohesion. An important factor in the success of the Ukrainian reform was the use of Poland’s experience in decentralization. The study highlights the positive aspects of the Polish local government reform and the possibilities of their implementation in domestic practice. The study of the Polish experience has also shown that in the process of administrative and territorial reform, it is necessary to take into account specific national characteristics and socio-economic realities. The theoretical and methodological basis of the study was formed by the scientific methods of synthesis and analysis, which rely on comparison and observation. The comparison method, by referring to the Polish local government reform, made it possible to identify common and distinctive aspects of the phenomenon under study and, on this basis, to highlight those that should be adapted to the Ukrainian model of territorial organization. It also enabled us to focus on mistakes that should be avoided. In turn, thanks to the observation method, we were able to study the trends that characterized the evolution of local self-government in Ukraine, to critically assess its transformation at each historical stage, and to identify the political factors that negatively affected this transformation. In the process of writing the article, a critical analysis of the literature on the subject, including the works of Polish and Ukrainian scholars and government officials, as well as the legislative framework of local self-government, played an important role.