• Bank sustainability performance are measured by a novel MCDM model. • Developed an objective method called LOPCOW for weighting. • Introduced a ranking method named DOBI. • LOPCOW-DOBI approach enables flexible decision-making. Banks do not directly contribute to sustainable development, yet they indirectly play an undeniable role. The sustainability of the banking sector, which is the heart of finance, is crucial both for this sector and economy as well as for the realization of the 2030 sustainable development goals. Despite the growing interest of practitioners and scholars on this issue, previous works are rare for developing countries. With a novel multi-criteria framework developed, therefore, this paper assesses banks in terms of sustainability and clarifies their levels of corporate sustainability performances. For the first time, this work introduces an objective weighting method named LO garithmic P ercentage C hange-driven O bjective W eighting (LOPCOW) with the advantages of eliminating the gap due to the size of the data, generating more reasonable weightings, and considering both positive and negative data in the weighting process. Further, a new multi-criteria method named DO mbi B onferron i (DOBI) is developed and utilized for deciding the ranking of the alternatives. The technique provides flexible decision-making, considering the risk attitude of decision-makers. The applicability of the proposed framework is demonstrated by a case study of Turkish banks. Banks are analyzed regarding the three pillars of sustainability and their seventeen drivers. The environmental pillar indicates the top significant impact on banks' sustainability. The “average return on shareholders' equity”, “electricity consumption”, “number of branches,” and “number of staff” are the top four key drivers for banks' sustainability. As a result of ranking the nine banks that release sustainability reports in Turkey concerning their sustainability performances, it is highlighted that Garanti BBVA outperforms the others. Wi...