The purpose of the paper is to outline the legal framework for the development of Ukrainian- Moldovan, Ukrainian-Slovak and Ukrainian-Romanian transborder regions (TBR), in particular in the context of intergovernmental agreements, national legislation on issues of cross-border cooperation, agreements between local authorities and regional cross-border regulatory support. The international cooperation of the Western region of Ukraine from the side of the authorities is focused mainly on the western vector, on relations with Poland. In our view, such regional policy leads to increasing regional differences in the socio-economic development of the Lviv and Ivano-Frankivsk regions, in particular their northern and southern parts. The intensification of the cross-border cooperation with Romania will create promising conditions for the transformation of a number of southern regions of the Carpathian region into a zone of accelerated economic development. This can be done through the development of transport, tourism and recreation, finance, logistics infrastructure, which will increase the attractiveness of the territories. And for this it is necessary to create an economic climate in the southern districts of the region, which would help attract foreign investment, especially Romanian, possibly by creating special or free economic zones there. The region has significant untapped potential of the Ukrainian-Romanian interaction that can be harnessed. The Ukrainian-Slovak and Ukrainian-Moldovan cooperation should also be strengthened in the region, the latter especially for the purpose of the European integration of Ukraine and Moldova. To this end, the article outlines the regulatory framework for the development of the Ukrainian-Moldovan, Ukrainian-Slovak and Ukrainian-Romanian transborder regions, in particular in the context of interstate agreements, national legislation on cross-border cooperation, agreements between local authorities and regional transborder security. The article describes the current state of subregional cooperation within the transborder regions, identifies the problematic issues of such cooperation, as well as reveals its content through the lens of the Euroregional cooperation. Methodogy. The dialectical method of scientific knowledge, method of analysis and synthesis, comparative method, method of data generalization are used in the paper. Results of the research. A description of the current state of subregional cooperation within the framework of the TBR is given, the problems of such cooperation are revealed, and its content is revealed through the prism of Euroregional cooperation. The key international projects of the development of the transborder regions were identified and their content and significance were analyzed for the improvement of the ecological safety of TBR, their entrepreneurship development, activation of innovation activities, the development of the border infrastructure, deepening of cultural interaction, improvement of urban development, revival of trade and investment activity in the above-mentioned transborder regions. The perspective directions of development of these TBRs are determined.