Decentralization of metropolises has been increasingly considered as an important strategy for creating a balance in development, economic productivity, and quality of life. The present study aimed to examine the role of local governments in decongesting metropolises. The present research method was conducted with a mixed approach. In the qualitative part, a semi-structured interview tool was used. Using the content analysis method and using MAXQDA.PRO.2022 software, data from interviews conducted with 15 academic experts were collected through three coding stages until saturation was reached through the thematic analysis. In the quantitative part, research questionnaires were distributed among 40 experts. Based on the data extracted from the questionnaire, an explanation of the conceptual model was presented. The research findings show that local governments have a direct impact on reducing urban density in the Tehran metropolis and their actions can help improve the living conditions of citizens. Effective coordination between local government departments is essential for achieving the goals of decongestion and sustainable development of urban areas. This research also concludes that the failure to strictly implement existing laws in the direction of decentralization and organization, disregard for the problematic dimensions of concentration, a one-point view of Tehran and failure to consider the urban area as a single whole, failure to simultaneously pursue organization and decentralization policies, and lack of strong will for decentralization are the most important factors in the failure of the effectiveness of decentralization and organization policies in reducing the dimensions of Tehran's issues and problems.