Over recent decades, the international financial system has been largely built upon infrastructures such as the SWIFT network and the dollar‑based settlement mechanism, a structure that has effectively enabled the use of financial pressure and sanctions against countries such as Iran. Iran’s restricted access to these infrastructures in recent years has led to significant disruptions in the country’s foreign transactions and banking interactions. In this context, the emergence of alliances such as BRICS and the Shanghai Cooperation Organization, along with the development of alternative systems like Russia’s financial messaging system and China’s Cross‑Border Interbank Payment System, has made the diversification of financial cooperation channels a key pillar of Iran’s economic diplomacy. The present study aims to design a model for expanding Iran’s banking cooperation with these alliances within the framework of financial diplomacy. The research adopts a qualitative approach based on grounded theory, with data collected through interviews with 41 experts in banking and economic diplomacy, as well as through analysis of international documents. The analytical process involved three stages—open, axial, and selective coding—through which the core category of “reducing the vulnerability of Iran’s banking system through diversification of financial cooperation infrastructures with Eastern economies” was identified. The findings indicate that obstacles such as technological limitations, secondary sanctions, concerns among Eastern banks regarding sanction risks, and institutional misalignment hinder effective cooperation; nevertheless, the gradual use of local currencies, collaboration with lower‑risk regional banks, and step‑by‑step integration into Asian payment networks could progressively strengthen Iran’s financial diplomacy capacity.