Numbers of one‐person households in East Asia have expanded dramatically in recent decades, especially among younger cohorts living in cities. In explaining this shift, research has largely addressed changes in socioeconomic and policy conditions that have interacted with family and marriage norms. This paper, however, is concerned with interactions of shifting urban and housing conditions that have channeled particular manifestations of single‐dwelling featuring shifts in housing pathways among younger‐adult cohorts toward living alone in rental housing. Focusing on Seoul and Tokyo as centers of growth, we consider how urban features, specifically housing markets and high‐speed renewal of the built‐environment, have shaped and contributed to the rise in one‐person households, as well as how the proliferation of singlehood and living alone is reshaping the lives of younger people in urban neighborhoods. This shift represents a particular disruption in social and spatial reproduction that has implications for cities in this region more generally.