This chapter explores the financing of green infrastructure as a foundation for advancing circular cities, which aim to minimise waste, optimise resource efficiency, and regenerate natural systems. It emphasises the role of banks as key intermediaries in mobilising capital for sustainable urban development through financial intermediation, specialised instruments, and capital market participation. The chapter highlights major sources of finance, including public funds, development bank instruments, carbon markets, and private capital, while discussing challenges such as regulatory constraints, risk perceptions, limited expertise, and inadequate data. It also examines strategies and innovations such as green bonds, blended finance, and green aggregation platforms that enhance project bankability. The chapter concludes that banks are central actors in aligning financial flows with the transition toward climate-resilient, circular urban systems.