In recent decades, cities have acquired a new role within the international relations system and have evolved from purely local actors into active participants in transnational interactions. One of the most important tools cities use to expand their influence and cooperation is sister-city relationships. In recent years, the city of Tehran has also concluded a number of sister-city agreements and memoranda of understanding with various cities around the world. However, studies indicate that many of these relationships have not been able to play an effective role in urban development due to the absence of a clear strategic framework, the lack of operational programs, managerial discontinuity, and an excessive focus on ceremonial interactions. As a result, many of these partnerships have remained limited to symbolic and short‑term activities. Therefore, revising and redesigning Tehran’s sister-city policies based on successful global experiences has become both necessary and unavoidable. The main objective of this study is to identify successful patterns of sister-city relations at the international level and to propose a framework for redesigning Tehran’s intercity cooperation policies. To achieve this objective, the research adopts a multi‑method approach, including a systematic literature review, thematic analysis, and expert evaluation. In the first stage, 318 documents related to intercity cooperation were identified. After screening based on criteria of credibility, relevance, and applicability, 40 successful global experiences were selected for more detailed analysis. In the next step, using thematic analysis, 212 basic themes were extracted from the data, each representing key dimensions of effective intercity relations. To validate and prioritize these themes in the context of Tehran metropolis, the views of eight experts and specialists in urban management and city diplomacy were collected and analyzed. Subsequently, the Friedman test was used to rank the importance of each cooperation axis.