PurposeThe purpose of this research is to reveal the impact of public legal protection on the efficiency of internal corporate governance in banks. In addition, this research proposes a new corporate governance index that could be employed by the banking sector to evaluate the performance of their internal corporate governance mechanisms.Design/methodology/approachOrbis database, annual reports and direct questionnaire are used to collect corporate governance data of 127 banks from 14 countries during 2020. The Mann–Whitney U-test is employed to compare the efficiency of corporate governance mechanisms based on three subsamples of countries having different legal protection levels (weak, middle and strong).FindingsThis research suggests a new corporate governance index for banks based on seven constructs and 62 variables. This new non-parametric index could be used by bankers to improve the monitoring process and enhance the overall performance of banking. The results of this research show that the existence of a strong public legal protection environment within a specific country enhances the efficiency of corporate governance mechanisms in the banking sector and thus, leads to improve the protection of shareholders, depositors and other relevant stakeholders. However, in countries that are characterized by weak legal protection level, the efficiency of corporate governance mechanisms is very low and there are possibilities of entrenchment, expropriation and extraction of private benefits. These findings could be interpreted within the prediction of agency, moral hazard, asymmetric information, political and entrenchment theories.Originality/valueThis research paper provides information that bankers and other relevant stakeholders in the banking sector working in MENA (the Middle East and North Africa) and European countries. A strong public legal protection level could improve the efficiency of internal corporate governance mechanisms within banks.