Of the build out of humanity predicted up to the end of the century, a substantial portion will occur within informal urban settlements – areas characterised by poor access to infrastructure and services. There is a pressing need to better understand how and with what implications the growing proliferation of Internet of Things (IoT) technologies, as a component of smart urbanism, are being applied to address the challenges of these areas. The following paper addresses this research gap, showing how IoT technology is reconfiguring trust within water and energy infrastructures in Nairobi. We apply work on informal urban infrastructures and smart urbanism to three case studies, producing novel insights into how IoT technologies reconfigure connections between users, providers and infrastructures. This reconfiguration of trust smooths chronic infrastructural uncertainties and generates reliability within informal settlements and, in doing so, leads to increased personal economies. We conclude by considering how these examples provide insights into the implications of IoT for everyday urbanisms in informal settlements and how these insights relate to global smart city debates more widely.