The literature on sustainability transitions increasingly recognizes that sectoral structures transcending national boundaries can both hinder and promote sustainability transitions. Yet there is only limited evidence on the roles of global actors in transforming entrenched socio-technical structures directly at the global scale. To explore the mechanisms of agency at the global scale, we develop a conceptual framework and illustrate it with a case study of the World Bank's engagement in the sanitation sector. Based on a Socio-Technical Configuration Analysis of World Bank project documents combined with expert interviews, we demonstrate how a paradigm shift in the global sanitation sector was initiated by a coalition of global advocates and subsequently promoted by the World Bank in its role as an amplifier. The paper thus further conceptualizes and illustrates a multi-scalar transition trajectory that depends strongly on advocacy by global actors.