The aim of the paper is to investigate the effect of Shariah governance mechanisms on the efficiency of Islamic banks in a sample of 56 Islamic banks in the GCC region over the period 2008-2020. The main results indicate that Shariah governance can improve the technical and scale efficiency of Islamic banks. The study shows that the introduction of new rules and regulations by policymakers can improve the efficiency of Islamic banks. This will be achieved by giving special emphasis to Islamic governance. our results provide policy makers, bank managers and investors with important insights into the determinants of the technical efficiency of Islamic banks. Policymakers may consider introducing new rules and regulations to improve the efficiency of Islamic banks by paying more attention to sharia governance. In addition, bank managers should consider improving the operations of Islamic banks to increase their market share. Furthermore, investors and customers can easily decide to invest in Islamic banks by referring to their efficiency scores.