Introduction. Ensuring budgetary stability and balance of the constituent entities of the Russian Federation on a long-term basis is the most important condition for ensuring macroeconomic stability in the constituent entities of the Russian Federation, creating prerequisites for the subsequent economic and investment development of the regions, and increasing the competitiveness of the financial and economic system of the Russian Federation. The work considers the components of the mechanism for ensuring the budgetary stability of the constituent entities of the Russian Federation. In the current financial and economic situation in Russia, fresh theoretical and methodological approaches to the definition of the concept of “financial mechanism”, “budgetary stability of the constituent entity of the Russian Federation”, which determine the budgetary stability of the constituent entity of the Russian Federation and improve the quality of budget planning and budget execution, acquire special importance. The purpose of the research is to formulate a scheme of the mechanism for ensuring the budgetary stability of the subject of the Russian Federation as a set of economic instruments, methods, forms and incentives. Materials and methods. The methodological basis of the study was the works of domestic and foreign scientists devoted to fundamental studies of the theory of the financial mechanism. The work considers the components of the financial mechanism for ensuring the budgetary stability of the constituent entities of the Russian Federation, the tools for its successful functioning. The theoretical foundations of the financial mechanism for ensuring the budgetary stability of the constituent entities of the Russian Federation are formulated, which is implemented through the use of a systematic set of tools, forms, methods and economic concepts that allow achieving the goals and objectives of budgetary policy, relying on the high quality of financial resource management and the growth of the investment attractiveness of the constituent entity of the Russian Federation for additional mobilization of financial resources. Research results, discussion. The constituent elements and tools of the mechanism for ensuring the budgetary stability of the constituent entities of the Russian Federation should be an interconnected, coordinated, dynamic system, and change in accordance with the development of the financial system of the constituent entity of the Russian Federation. Conclusion. The integrated financial mechanism for ensuring the budgetary stability of the constituent entities of the Russian Federation should be the basic link in the modernization of the regional financial system.