["International Journal of Urban and Regional Research, EarlyView. ", "\nAbstract\nThis article outlines possibilities for counter configurations of data‐based urbanisms, whereby data practices, rather than reproducing logics of urban entrepreneurialism and smart‐city governance, are made from within urban peripheral territories. Drawing on participatory action research with a data activism collective in the favela of Maré, Rio de Janeiro, we explore how datafication as an epistemic practice is reappropriated as an embodied and territorially situated practice of political agency. Mobilizing Latin American debates on body‐territory, and in dialogue with subaltern urbanism, we develop the notion of subaltern data—a grounded data that gains political force through the entanglement of bodily markers, lived experience and territorial knowledge. We show that counter practices of urban datafication, and their political effects, emerge through contingent, ambivalent and negotiated encounters with both state institutions and territorialized publics. Subaltern datafication, operating both as an instrument for activism and a situated epistemological frame, is aimed at producing new visibilities of the urban periphery through the coming together of the subaltern body and data knowledge infrastructures. Yet, in embracing the epistemic language of the hegemon, subaltern data operates within, rather than transcends, the epistemological limits of subalternity; a tactic that does not resolve but negotiates the subaltern condition.\n"]