Cities are currently being redesigned with sensors and data at their core. Environmental monitoring, crime tracking and traffic mapping are just a few examples of the socio-technical systems that are remaking cities. These systems are emergent sites of politics, values, and ethics where human and nonhuman actors collaborate, negotiate and debate the futures of their cities. One the one hand, they can be used for prediction, measurement and decision-making, but, on the other hand, they can also be harnessed to imagine alternative possible urban futures. Designers have an important role to play in mediating, making sense of, and intervening in these projects, which are at the intersection of the work of a variety of stakeholders including governments, business and citizens. This article draws on science and technology studies (STS) to think through ways designers can evolve existing human-centered design (HCD) methodologies to contend with socio-technical complexity at a time of great economic and environmental crisis. In particular, this article argues that it is necessary to create and explore methodologies that decenter the human and take the nonhuman seriously in order to meaningfully engage in the design of cities with more responsible, accountable, and ethical ways of engaging with emerging technologies.