This article proposes a cyborg reading of the process of informal settlement by internal and postcolonial immigrants in Lisbon’s periphery from the 1970s to the present. Cyborg does not stand for a neo-organicist or cybernetic understanding of the informal city but rather for the conjunction of the multiple enactments of city life under conditions of urban informality—in this case the fourfold combination of history/migration; architecture/low-fi technologies; inhabitation/body/memory; and governmentality/urban capital. The 40-year event of settlement and inhabitation is presented through an ethnographic micro-history of one neighbourhood in particular, with a strong focus on slum dwellers’ life stories, on the details of the artefact-machines they have built, their informal dwellings, and on their social and mental experience of place. Responding to recent calls for multidisciplinary ethnographies of informality, the article brings the specificity of Lisbon’s informal settlements—their growth based in postcolonial rather than rural migrations—into current debates on informal urbanisms and geographies of sociotechnical urban assemblages.