Islamic Sustainable Banking as a Mediating Mechanism Between Financing Structures and Bank Performance: Evidence from Indonesia and Malaysia

Islamic banking is increasingly expected to align Sharia-based intermediation with sustainability objectives, yet empirical evidence remains limited on how sustainability disclosure links financing structures with bank performance. This study examines whether Islamic Sustainable Banking (ISB) functions as a mediating mechanism between profit-sharing financing, debt-based financing, and financial performance in Islamic banks in Indonesia and Malaysia. ISB is measured using an Islamic Sustainable Banking Disclosure Index that integrates Maqasid al-Shariah principles with SDG-oriented disclosure indicators. Using panel data from 23 Islamic banks over 2018–2023 and applying partial least squares structural equation modeling, mediation analysis, PLS-MGA, and permutation tests, the study finds that both profit-sharing and debt-based financing are negatively associated with ISB disclosure, while ISB is positively associated with net profit margin but not return on assets. The mediation results indicate statistically significant negative indirect associations through ISB, suggesting that sustainability disclosure operates as a conditional transmission mechanism rather than an automatic performance driver within the specified PLS-SEM model. Cross-country tests reveal significant differences between Indonesia and Malaysia, particularly in the associations between financing structures and profitability. The study contributes to Islamic sustainable finance by clarifying how Maqasid-oriented disclosure connects financing composition, governance capacity, and profitability, while offering practical implications for bank managers, regulators, and policymakers seeking to integrate sustainability into Islamic banking governance and financing decisions.