["Corporate Social Responsibility and Environmental Management, EarlyView. ", "\nABSTRACT\nAgainst the strategic context of China's accelerated push for green transformation in manufacturing and the pursuit of “dual carbon” targets, this paper examines how green factory certification (GFC) shapes the expansion of firms' green innovation boundaries. Based on a panel dataset of Chinese A‐share listed industrial enterprises covering 2010–2023, we exploit the multi‐phase rollout of GFC as a quasi‐natural experiment and employ a staggered difference‐in‐differences approach. Results indicate that GFC significantly drives the outward expansion of enterprises' green innovation boundaries, and this conclusion remains consistent after a battery of validation tests, including parallel trend analysis, heterogeneous treatment effect assessment, and corrections for self‐selection bias. Heterogeneity analysis reveals that the expansion effect is insignificant for small and medium‐sized enterprises and for firms with stronger greenwashing incentives. Mechanism tests verify four underlying channels: enhanced resource acquisition, embeddedness in collaborative innovation networks, participation in green technology standard alliance networks, and green upgrading of supply chain networks. Further analysis uncovers a technology‐biased effect; GFC only promotes boundary expansion in fossil fuel carbon reduction and carbon capture, utilization, and storage. Spillover analysis demonstrates heterogeneous externalities on uncertified firms; GFC encourages green innovation boundary expansion among cross‐industry firms within the same city, yet exerts a crowding‐out effect on industry peers.\n"]