Going beyond the mere gender diversity in the boardroom, this systematic review comprehensively covers the research on board diversity of financial institutions. More specifically, we cover gender diversity, as well as other characteristics of diversity, such as nationality, age, tenure, experience, education, ethnicity, and religion. A systematic literature review was employed using Scopus and Web of Science databases, covering all publications until May 2020, which resulted in 91 studies from 66 top‐ranked journals in accounting, finance, and economic fields. We analyze them based on the journal, methodology, research construct questions, and theoretical perspectives. Our results highlight the substantial knowledge gaps and the inconsistent findings of prior studies on several aspects of the field, suggesting avenues for further studies in terms of research designs, settings, scope, and theories. We argue that there is a need to explore other board diversity attributes rather than focusing on the gender diversity of the boards of financial institutions to achieve sustainable development. Also, more work is outlined on topics related to board diversity of financial firms that receive limited attention from scholars, such as (but not limited to) environmental performance, capital structure, intellectual capital, innovation and earnings quality of financial institutions, as well as the indirect effect of policy settings.