Urban informality has long been theorized as a spatial condition of urban life—an expression of negotiation, improvisation, and survival within the uneven terrains of legality and governance. Yet this emphasis on space has obscured the temporalities through which informality is lived, governed, and contested. This essay develops the concept of ‘nocturnal informality’, drawing on experiences of street trading in Harare to foreground the night as a critical yet neglected temporal frontier of informal urbanism. Drawing on urban political theory and literature on the urban night, I argue that nocturnal informality reveals how the urban poor navigate shifting regimes of visibility, surveillance, and regulation across temporal rhythms. The night, I suggest, is not merely a temporal void but a socially and politically charged space-time in which informal practices unfold amid darkness, opacity, and affective intensity. Conceptually, nocturnal informality sharpens our understanding of how the local state is remade through the rhythmic and temporal dynamics of the urban night.