This paper examines the role of bank-specific, macroeconomic, and regulations on the performance of Islamic and conventional banks in ASEAN countries over the period 2009-2016 using a fixed-effects estimator. The results indicate that conventional and Islamic banks were significantly affected by the operating cost. We find the significant effects of bank concentration and credit risk on conventional banks' performance. For Islamic banks, we uncovered evidence suggesting that diversification and liquidity risk are important determinants of the performance of Islamic banks. Interestingly, the findings indicate that regulations are the key drivers of the performance of Islamic banks. Activity restrictions, supervisory power and Islamic regulation have a significant impact on the Islamic banks' performance. The findings highlight policy implications in improving bank performance, including reducing operating costs, less stringent supervisory power, robust Islamic regulation and effective risk management.