This study investigates how customer concentration shapes corporate social responsibility (CSR) reporting, focusing on the distinct roles of government and foreign customers—a critical yet underexplored dimension in the age of climate crisis and evolving multi-stakeholder governance. Using panel data from 105 firms listed on the Tehran Stock Exchange (2013–2022), we examine three customer concentration metrics and their relationship with CSR disclosure. Our results reveal a significant negative association between customer concentration and CSR, suggesting that firms reliant on a few dominant buyers deprioritise sustainability initiatives, potentially exacerbating environmental and social risks in supply chains. However, government customers emerge as a countervailing force, moderating this relationship by embedding socio-environmental mandates into contracts—a finding with profound implications for policymakers aiming to align corporate behaviour with climate goals. Surprisingly, foreign customers fail to drive CSR improvements, underscoring how geopolitical barriers (e.g., sanctions) can disrupt global sustainability norms. The study advances the multi-stakeholder governance paradigm by demonstrating that: 1. Customer power dynamics directly influence firms’ ability to meet the triple bottom line (profit, planet, people), with concentrated buyers often undermining environmental commitments; 2. Government intervention can strategically recalibrate this tension, offering a model for regulating CSR in high-emission industries; 3. Geopolitical fragmentation (e.g., sanctions) may inadvertently weaken transnational CSR pressures, highlighting the need for adaptive governance frameworks in a polarised world. By bridging customer strategy, climate accountability, and stakeholder theory, this research provides actionable insights for: • Firms navigating trade-offs between buyer dependence and sustainability; • Policymakers designing climate-aligned procurement rules; • Global governance bodies addressing CSR decoupling in sanctioned economies. Our findings underscore that in an era of climate urgency, customer characteristics are not just commercial concerns but governance levers—with the power to either accelerate or impede the transition to sustainable, multi-stakeholder capitalism

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