This article traces the formation of the International Migrants Alliance (IMA) through a study of its leading organisations and central campaigns. Founded in 2008 by 108 self-described ‘grass-roots’ migrant organisations, the IMA is a transnational coalition of groups from nearly every continent of the world. I suggest that through their work in IMA, migrants express a new form of political subjectivity, a form of ‘migrant labour transnationalism.’ Migrant labour transnationalism, unlike the homeland-oriented, citizenship-based, state-supportive forms of migrant political transnationalism generally identified in the scholarship, is based on counter-hegemonic nationalisms through which migrants contest their home states’ complicity with the project of neoliberal globalisation. Migrant labour transnationalism is, moreover, formed through contentious forms of political engagement and new transnational networks through which migrants are cultivating class-based collective identifications.