Informal workers produce economic, social, and environmental value for cities. Too often, policy elites, including those promoting sustainable cities, overlook this value, proposing formalization and relying on deficit-based framings of informal work. In this perspective piece, we bring critical research and community-produced knowledge about informal work to sustainability scholarship. We challenge the dominant, deficit-based frame of informal work, which can dispossess workers, reduce their collective power, and undercut the social and environmental value their work generates. Instead, thinking historically, relationally, and spatially clarifies the essential role of informal work for urban economies and highlights their potential for promoting sustainable cities. It also reveals how growth-oriented economies reproduce environmental destruction, income inequality, and poverty, the very conditions impelling many to informal work. Rather than formalization, we propose reparation, an ethic and practice promoting ecological regeneration, while redressing historic wrongs and redistributing resources and social power to workers and grassroots social movements.