Urbanization is a global phenomenon with strong sustainability implications across multiple scales. We argue that much of the associated challenges, and opportunities, are found in the global south. We show that urban issues in the global south are distinctly and statistically different from those in the global north, but our current urban knowledge is predominantly shaped by research on and from the global north. Cities in the global south have strong imperatives, and unique but often overlooked capacity, to innovate and experiment for sustainability. We call for a renewed research focus on urbanization in the south, and suggest targeted efforts to correct structural biases in the knowledge production system.