With increasing attention being paid to corporate sustainability, pressure from stakeholders, especially customers, is forcing companies to implement sustainability strategies and practices that express their commitment to sustainable development, and engage with stakeholders through voluntary sustainability disclosure. To better understand the sustainability disclosure mechanisms from a business strategy perspective, this study investigates the influence of business strategy, formulated by customer groups, on online sustainability disclosure. It provides empirical observation of Malaysian public‐listed companies based on the combined lens of stakeholder and legitimacy theory. Despite the comparatively low level of corporate sustainability disclosure in Malaysia, this content analysis of online sustainability information disclosure reveals that the companies with more diversified product lines disclose more sustainability information, and that the corporate sustainability effort is significantly related to brand name. Hence, companies should be encouraged to proactively improve their sustainability performance and disclose more sustainability information in order to strengthen their brand names. Copyright © 2013 John Wiley & Sons, Ltd and ERP Environment