A stable financial system plays a critical role in facilitating the flow of funds from savers to investors and optimal allocation of scarce resources to productive economic activities. Any disruption in the functioning of this system can jeopardize these essential objectives. Economic uncertainty, as a key factor affecting economic decision-making, has always been the focus of policymakers. This study aims to provide a comprehensive analysis by calculating an uncertainty index arising from Iran's economic policies (including monetary and exchange rate policies) during the period 1981–2022 using the GARCH model and the OECD’s ten-step methodology. Furthermore, the relationship between the economic policy uncertainty index and the financial stability index was examined using the Markov Switching model. Key variables affecting monetary policy uncertainty include interest rate, money supply growth rate, inflation rate, central bank independence, and government fiscal health, while the key variable for exchange rate policy uncertainty is the real exchange rate. The financial stability index was constructed using variables such as liquidity, capital adequacy ratio, bank credit to the private sector, deposit interest rates, stock market index, and exchange rate. The findings reveal that EPU1 primarily reflects domestic economic fluctuations, while EPU2 is more sensitive to international shocks like sanctions. During financial instability, external shocks dominate, whereas both domestic and external uncertainties pose threats during stable periods, highlighting the need for adaptive policy measures to maintain financial stability in Iran's economy."