["Business Strategy and the Environment, EarlyView. ", "\nABSTRACT\nAs global climate physical risks intensify, localized extreme weather events increasingly trigger systemic supply chain disruptions, posing a severe but often overlooked threat to corporate sustainability. Although existing literature predominantly focuses on a firm's direct exposure to climate shocks, the indirect transmission of these physical risks through upstream supply networks remains critically underexplored. To bridge this gap, this study constructs a novel Supplier Climate Physical Risk (SCPR) index by mapping granular meteorological data to the geographical footprints of key suppliers for Chinese A‐share listed firms over the 2011–2023 period. Our empirical analysis reveals a profound penalizing effect: A one‐standard‐deviation increase in upstream climate risk leads to a decrease of approximately 4.7% of a standard deviation in the downstream focal firm's overall Environmental, Social, and Governance (ESG) performance. By unpacking this aggregate shock, we uncover a multidimensional transmission mechanism driven by supply chain disruption risks. Specifically, upstream climate turbulence simultaneously stifles interfirm green collaborative innovation (the ‘E’ channel), crowds out corporate social responsibility (CSR) investments due to emergency resource reallocation (the ‘S’ channel), and induces managerial myopia (the ‘G’ channel). Furthermore, this penalizing effect is mitigated for state‐owned enterprises, firms with diversified suppliers, and environmentally aware executives. Ultimately, this study advances the intersection of supply chain resilience and corporate sustainability, providing compelling evidence that mitigating upstream physical climate risks is imperative for safeguarding long‐term ESG strategic goals.\n"]