The object of this research is budget expenditures. The limited financial resources are typical for most countries of the world, therefore, it is important to find and improve the ways of forming and implementing the budgetary policy of the state at every stage of the budgetary process. The budget of any country reflects important economic and social aspects of the life of society as a whole and each person individually. Of course, the budget is a powerful regulator of the main economic processes. One of the most problematic areas is ineffective and inefficient use of budget expenditures. Therefore, this study is aimed at developing practical recommendations for optimizing the process of managing budget expenditures in the context of decentralization to ensure sustainable socio-economic development of the state. To achieve this aim, the author used the problems of managing budget expenditures on the example of Ukraine in the context of the introduction of decentralization processes in the country. The research used the methods of scientific abstraction, systems approach, grouping and classification. To determine the integrated indicator of the efficiency of budget expenditures management at the level of a budgetary institution, society, region, state, a statistical method was used that reflects the correlations of the constituent indicators. To optimize the process of managing budget expenditures, which is considered as a cycle of public policy, two main approaches are proposed. First, a change in the concept of budget expenditures management – a transition from the consumption budget to the development budget, which will allow achieving sustainable economic development in the long term. Secondly, it is proposed to introduce an assessment of the effectiveness of budget expenditure management by calculating an integrated indicator, consisting of all components that reflect the effectiveness of the budgetary policy being implemented. Thanks to the proposed methodology, it is possible to timely adjust the policy for managing budget expenditures in the event of an unsatisfactory value of the integrated indicator of the effectiveness of managing budget expenditures. This provides the advantage that such an adjustment will have a positive effect, since it will be carried out both at the level of a budgetary institution, society, region, and the state as a whole.