Multinational corporations (MNCs) today have substantial interests in private voluntary standards, such as those set by the International Organization for Standardization (ISO), as they have become a significant and contentious area of international business institutions. How do MNCs influence the creation of these private standards? This paper argues that MNCs utilize their global subsidiary networks to exert influence in international private regimes. Specifically, the one-country-one-vote system in the ISO standardization process incentivizes MNCs to leverage their connections with host countries---particularly those previously inactive in standard-setting---to garner the votes needed for standard approval. Using original panel data on voting membership across 758 ISO technical committees, covering 165 countries from 2007 to 2017, the  findings reveal that national standard developing bodies are more likely to participate in standardization in areas where they have received related inward foreign direct investments. Furthermore, utilizing information on project leaders for each ISO standard, the study identifies firms with specific interests in establishing certain standards. The results demonstrate that investments from these firms specifically lead to host country participation in the relevant standard-setting areas. These findings suggest that certain international institutions may disproportionately empower MNCs compared to  firms without global subsidiary networks.