Finance that does not take sustainability seriously is finance that does not take finance seriously. The financial risks of continued unsustainabilities bring sustainability issues into the heart of any well-founded financial decision, whatever view one might have on the role of finance and business in society. In this chapter, the relationship between finance and sustainability is explored through a broadening of the approach to understanding financial risks of unsustainability. This goes beyond the established recognition of the financial risks of climate change – and the emerging recognition of financial risks of biodiversity loss. The analysis presents new risk categories, including the risk of business model change, societal risk and global catastrophic risks. The chapter also exemplifies new categories of unsustainability that should be encompassed in such a broader and systemic approach, including ‘novel entities’ and tax evasion. The chapter concludes with brief reflections on the necessity of and the legal basis for implementing a research-based approach to risks of unsustainability in law and policy reforms and in practice.