This study seeks to explore the information value of financial metrics on corporate sustainability and investigate the moderating effects of institutional shareholders on the association between net cashflows (NCF) and corporate sustainability of the leading ASEAN countries. The dataset consists of companies listed on the Stock Exchange of Thailand, Malaysia and Singapore during 2013–2023. Fixed effects panel regression is executed in this study. Subsequently, the conditional effects served to evaluate the influence of institutional shareholders on the association between NCF and corporate sustainability. This study employs agency theory to explore how the alignment of institutional shareholders influences sustainability outcomes. This study found that institutional shareholders themselves supply information for the sustainability indicator in Thailand and Singapore, but not in Malaysia. Furthermore, adversely correlated with sustainability metrics in all three nations is the interaction term between institutional shareholders and net cashflows. Further investigation reveals that for each nation’s sustainability measures the institutional shareholders offer value relevant to net cashflows at certain amounts. This study not only contributes to existing academic research on sustainability and financial indicators, it also provides practical strategies for companies and investors trying to match financial performance with sustainability goals in a fast-changing global market.