Sanctuary and solidarity movements have motivated an expansive body of scholarship identifying cities as key sites of political community-building. However, we have not yet found a theoretical approach to understand two problems related to these movements. Firstly, we have not yet historicised their underlying logics. Secondly, we do not yet systematically understand the shared features of these practices nor what might bind their guiding aims and implications. In response to these lacunae, I advance a critical cosmopolitanism grounded in the solidarities expressed by urban migrant-rights movements. I argue that the two key conditions of presence and encounter illuminate (1) the shifting use of the term ‘cosmopolitanism’ from a tradition of norms espoused by Immanuel Kant to the description of experiences of itinerancy and mobile relation indicated in Achille Mbembe’s afropolitanism, and (2) the relevance of cities, which sustain the relations foundational for global solidarity, in an emerging global public sphere.