In the 21st century, a growing number of people live ‘informal’ lives within fissures between legality and informality. Concomitantly, power relations are increasingly expressed through devices of confinement. While urban informality and confinement are on the rise often occurring simultaneously, scholars have so far studied them separately. By contrast, this article proposes a new framework for analysing urban informality and confinement relationally. It generates new insights into the role of informality in the (re)production of confinement and, vice versa, the role of confinement in shaping informal practices. While these insights are valuable for urban studies in general, the article charts new lines of research on urban marginality. It also discusses how the six articles included in this special issue signal the heuristic potential of this relational framework by empirically examining distinct urban configurations of ‘confined informalities’ and ‘informal confinements’ across the Global North and the Global South.