This article investigates the agency of the world’s largest food and agribusiness corporations in global water security via case studies of Nestlé, Bunge and Cargill by analysing their position in the political economy of the world agro-food system and the ways they intentionally and non-intentionally manage and govern water in their value chains and wider networks of influence. The concentrated power of a few corporations in global agro-food value chains and their ability to influence the agro-food market dynamics and networks throughout the world pose asymmetric conditions for reaching not only global food security but also water security. The article will analyse the different forms of power exercised by the corporations in focus in relation to global water security and the emerging transnational water governance regime, and the extent to which their value chain position and stakeholder interaction reflect or drive their actions. Due to their vast infrastructural and technological capacity and major role in the global agro-food political economy, food and agribusiness corporations cannot avoid increasingly engaging, for endogenous and exogenous reasons, in multi-stakeholder initiatives and partnerships to devise methods of managing the agro-food value chains and markets to promote global water security. However, their asymmetric position in relation to their stakeholders demands continuous scrutiny.