This special issue sheds light on transnational migrants’ engagement with informal urban economies worldwide. Building on anthropological literature on migration and economy, it proposes “transnational street business” as a new concept for grasping transnational dynamics in the informal urban economy. Through ethnographic case studies from different regions, the special issue illuminates how the concept of “transnational street business” serves to analytically capture the urban street's multitude of economically entangled and interdependent transnational social alliances, hierarchies, friendships, and networks. The concept encompasses the materiality of the street and the goods that are exchanged and transacted in trade relations. It also highlights the skills for competition that are needed for orientation in legal and political landscapes that cut across the formal and informal divides that migrants are faced with when setting out to create a livelihood abroad.