This study investigates whether a firm can enhance its competitive advantages in intangible assets and financial performance by voluntarily obtaining the certification of environmental management system ISO 14001. Previous studies find mixed evidence for the effect of ISO 14001 certification on firm performance partly owing to sample selection bias. To overcome this bias, we utilize propensity score matching to find non‐certified firms that are comparable to certified firms. The evidence from our matching method suggests that ISO 14001 certified firms have higher values of intangible assets than non‐certified firms. Our study thus suggests that stakeholder engagement in firms' environmental management can be beneficial not only to the public, but also to shareholders. Copyright © 2017 John Wiley & Sons, Ltd and ERP Environment