As a key tool to drive the green transformation of enterprises, the implementation effectiveness of green finance policies is directly tied to the micro-level realization of the green development concept. The policy of Green Finance Reform and Innovation Pilot Zones promulgated in 2017 marked a new stage of green finance in China. However, the green transformation pressure faced by core customers in pilot zones transmits upstream to non-pilot zone suppliers, which may induce resource-constrained suppliers to resort to “greenwashing” to evade compliance pressure. Existing studies mostly focus on the direct impact of green finance policies on pilot-zone enterprises, neglecting the unintended consequence transmitted through supply chains. Moreover, discussions on the causes of “greenwashing” rarely involve upstream-downstream relationships in supply chains, resulting in a notable research gap.

Based on a sample of A-share listed companies from 2012 to 2022, this paper examines whether green finance policies will trigger the unintended consequence of “greenwashing” among non-pilot-zone suppliers through the supply chain spillover effect from the perspective of supplier-customer relationships, and further analyzes the underlying mechanisms. Empirical results show that customer enterprises in Green Finance Reform and Innovation Pilot Zones significantly induce “greenwashing” behaviors among non-pilot-zone suppliers, revealing the supply chain transmission characteristics of policy impacts. In terms of mechanisms, pilot-zone customers, through the transmission of supply chain pressure, not only raise suppliers’ environmental protection costs and exacerbate their operational pressure, but also strengthen suppliers’ motivation to cater to major green customers. These two factors jointly drive suppliers’ “greenwashing” behaviors. Heterogeneity analysis indicates that major customers in pilot zones exert a more pronounced effect on “greenwashing” among non-pilot-zone suppliers with lower customer stability, weaker executive green awareness, and lower media attention.

By incorporating supply chain networks into the analytical framework of the green finance policy effect, this paper not only expands the theoretical boundary of “greenwashing” research, but also provides direct empirical evidence for improving the cross-regional collaborative supervision mechanism and optimizing the allocation of green financial resources, which holds important practical significance for promoting the sound development of green finance.