This chapter explores the persistent financial barriers confronting small and medium-sized enterprises (SMEs) in adopting circular economy models across global contexts. While circular SMEs offer transformative solutions for resource efficiency, waste reduction, and environmental sustainability, they remain severely underfunded. The chapter identifies key constraints such as capital intensity, extended payback periods, risk perception, limited access to impact-oriented investors, and the misalignment between conventional financial products and the unique realities of circular ventures. It illustrates how structural mismatches between financial systems and SME needs impede progress. The study also examines innovative responses such as blended finance, ESG-integrated fintech solutions, and SME aggregation platforms that offer promising avenues for inclusive financing. The chapter concludes by proposing policy and ecosystem reforms to build a more supportive financial environment capable of enabling circular SMEs to scale and thrive in both advanced and emerging economies.