Sustainable finance is fundamental for the realisation of sustainable development and addressing environmental, climate and social challenges to ensure an inclusive economy for all. At a macroeconomic level, sustainable finance is essential for economic growth. In a developing country such as South Africa where Small and Medium Enterprises (SMEs) play a crucial role in the overall economic development and where a vast number of the population is made up of vulnerable financial consumers, studies on sustainable finance have become urgent and vital. While climate change and related natural disasters such as floods, wildfires, rising temperatures, and shifts in weather patterns continue to be a global challenge, access to financial services and products has become increasingly vital to assist SMEs and vulnerable financial consumers in coping with climate change shocks and becoming financially resilient. Despite some research being conducted on the financial sustainability of SMEs and the financial inclusion of vulnerable consumers, there has not been much attention paid to the specific and special role of banks and financial institutions in facilitating sustainable finance from a law and economics perspective. Sustainable finance is important to integrate struggling financial consumers into the formal economic activities in South Africa. This chapter seeks to close the knowledge gap by examining the role of banks and financial institutions in facilitating access to sustainable finance for SMEs and vulnerable financial consumers to ensure their financial well-being and resilience. Desktop-based qualitative research was conducted to examine a law and economics approach to the role of banks and financial institutions in promoting sustainable finance. There is a need to use financial services to increase resilience to climate change-related shocks by developing impact-conscious policies and legal frameworks on access to sustainable finance products and services.