The purpose of this article is to identify the long-term economic consequences of mine decommissioning for five selected cities located in Poland in the Upper Silesian Coal Basin. It is carried out over a period of 18 years and covers the period 2003–2020. The economic effects of decommissioning are examined in the context of the budgets of cities where mining plants were closed. In the course of the analyses, the authors of the article attempt to answer the following research questions: (1) has the decommissioning of the mines influenced the current and strategic situation of the examined cities in terms of their budgets? (2) Have the examined cities felt the economic effects of mine decommissioning in a similar way? The assessment of the economic effects of mine decommissioning was carried out from the following two perspectives: (1) operational, relating to the balance of local budgets, and (2) strategic, taking into account the level of long-term liabilities of the examined cities. As part of the research methodology, budget analysis, descriptive statistics, dynamics and trends analysis, correlation and comparative analysis were used. The research carried out in the article shows that the decommissioning of hard coal mines in the examined cities of the Upper Silesian Coal Basin had a negative impact on the balance of local budgets and the level of long-term debt. This was especially true in the cities where all the mines had been decommissioned and which had no way of replacing the mining industry with other economic alternatives. The cities with more diversified economic activity and sources of income were in a better economic condition.