This study explores the implementation of sustainable finance in an Indonesian state-owned bank (“ABC Bank” or “ABC”). A case study approach is employed to deeply analyze the implementation using data collected through interviews and through a review of company documents. The frameworks from Soppe (2004) and Indonesia Regulation POJK 51 were used to examine the sustainable finance implementation. The findings show that ABC Bank exercises a sustainability commitment in implementing sustainable finance long before the government regulation is imposed on several banks as early adopters in Indonesia. The regulation requires selected banks to apply the eight principles of sustainable finance and prepare a sustainable financial action plan and sustainability report. ABC’s commitment is mainly driven by its status as a government-owned bank, thus facilitating the awareness of achieving public welfare while maintaining profitability. Social implication of this study is that developing countries often face more severe consequences of climate change than developed countries. Hence, the sustainable finance implementation can have a significant social impact to reduce the negative effect. This study contributes to the literature by exploring the initial adoption of sustainable finance by a state-owned bank attempting to balance the interests of the public and management. It also provides insights into other financial institutions adopting sustainable finance as mandated by the local obligation POJK 51.