With the deepening of economic integration, the interdependence between upstream and downstream firms in the supply chain continues to intensify. Using data from listed firms in China from 2010 to 2023, we empirically examine the contagion effect of suppliers' environmental misconduct on the green innovation continuity of downstream firms, testing the related mechanisms and policy shocks. Our findings reveal that suppliers' environmental misconduct significantly undermines downstream firms' green innovation continuity. Additionally, suppliers' environmental misconduct decreases downstream firms' green cognition of executives and increases their corporate financial constraints, thereby reducing the green innovation continuity of downstream firms. Further, the increase in bargaining power of downstream firms can weaken the negative impact of suppliers' environmental misconduct on downstream firms' green innovation continuity. However, the closer the geographic distance between upstream and downstream firms, the more severely supplier environmental misconduct reduces the green innovation continuity of downstream firms. We further find that with the implementation of China's new environmental protection law in 2015, suppliers are intervened to reduce their environmental misconduct, thus favoring an increase in green innovation continuity for downstream firms. Our findings add to the green supply chain literature, provide a perspective of green innovation continuity for corporate governance, and extend the research on the shock of exogenous green laws on firms.