Government debt sustainability is one of the most important challenges facing resource-dependent economies, particularly oil-exporting countries. Since oil revenues can influence governments’ fiscal performance and their ability to meet financial obligations, this study aims to analyze the dynamic effects of oil revenues on government debt sustainability in nine selected oil-exporting countries, namely Iran, Saudi Arabia, Kuwait, Qatar, Nigeria, Norway, Canada, Mexico, and Oman, over the period 1996–2024 using the Pooled Mean Group (PMG) approach. Government debt sustainability is evaluated within the framework of Bohn’s Fiscal Reaction Function, employing the primary fiscal balance as the indicator of fiscal response. The estimation results indicate that oil revenues have a positive and statistically significant effect on the primary fiscal balance in the short run, whereas their long-run effect is negative and statistically significant. These findings suggest that, although oil revenues can improve governments’ fiscal positions and strengthen debt sustainability in the short term, long-term dependence on these revenues and their associated volatility weakens governments’ ability to maintain debt sustainability. Furthermore, the negative and statistically significant coefficient of the government debt-to-GDP ratio in the long run indicates that the positive fiscal response predicted by Bohn’s Fiscal Reaction Function is not observed in the selected countries. In addition, economic growth and institutional quality positively affect the primary fiscal balance, while inflation exerts a negative effect. Therefore, efficient management of oil revenues, strengthening institutional quality, and implementing prudent fiscal policies can play an important role in enhancing government debt sustainability in the selected oil-exporting countries.