This chapter maps the scientific landscape on sustainability transparency in the banking sector, identifies and reviews relevant transparency dimensions, and highlights relevant theories and research gaps. For this purpose, a hybrid literature review is conducted based on 489 peer-reviewed papers indexed in Scopus for the period 2000–2023. A mix of quantitative tools (Bibliometrix R, VOS Viewer, SciVal, InfraNodus) and procedures (PRISMA, Citation Count Regression) is applied, with a focus on the relevance of legitimacy theory, stakeholder theory, and the multistakeholder approach. Sustainability transparency relevant to banks is viewed as a multi-dimensional construct related to disclosure efforts from the perspective of Environmental, Social, and Governance criteria (ESG). The literature review suggests that an understanding of sustainability transparency in banking should also explicitly account for the Sustainable Development Goals (SDGs), which is currently not the case. The literature shows that a lack of transparency can lead to the erosion of social trust and legitimacy through green- and other types of washing. Yet when stakeholders’ most material needs for transparent and credible information are met, good governance can prevail. The chapter elucidates why sustainability transparency benefits standard-setters and policymakers in the banking sector. It indicates potential areas for improvement of bank governance and supervision towards more transparent and credible bank disclosure in the European Union.