Governance is widely recognized as a critical factor influencing sustainable development. Consequently, analyzing its dimensions can significantly contribute to economic and policy-related insights. This study investigates the impact of uncertainty in good governance indicators on sustainable development in Iran, utilizing fuzzy regression analysis with a membership degree of 0.9 over the period 1995–2020. Owing to the inherent flexibility of the fuzzy regression model, high, medium, and low widths were calculated for each of the examined variables under uncertainty conditions (membership degree 0.9). Drawing on the relevant literature on good governance and sustainable development, three models were estimated. The first model assesses the impact of governance indicators based on Briguglio's definition. Results show that the economic stability index exerts minimal influence on sustainable development across all three scenarios. The effect of the political stability index remains relatively constant, while the social stability index—with a width of 0.556—exerts the greatest impact. The second model examines the six governance indicators defined by the World Bank. Findings indicate that governance efficiency and effectiveness have the most significant influence on sustainable development, with a coefficient of 5.5. The third model, which combines elements of the first two, reveals that the political stability index consistently affects sustainable development in all three scenarios, with a coefficient of 0.742. Overall, the results confirm that uncertainty in good governance indicators has a substantial effect on sustainable development. The actual trajectory of sustainable development in Iran corresponds more closely with the lower and left bounds of the fuzzy regression range, suggesting that governance-related uncertainty acts as a limiting factor.