There has been an emerging interest in the study of urban design dimensions associated with Transit-Oriented Developments (TODs). However, addressing the question of how TOD principles laid out in the international literature can be explored in the context of the global South remains in an incipient stage. In this paper, we investigate the nexus between station walkable catchments and forms of urbanity around transit nodes by adopting an assemblage approach to cut across any separation of sociality and spatiality. Drawing on empirical research from two case studies in Tehran, this paper contributes to studies on transit urban design by developing two measures of accessibility—the Catchment of Accessible Public Spaces (CAPS) and Accessible Interfaces (AI). We found that the combination of high CAPS and high AI within a given time can enable streetlife intensity, which is also linked to a synergistic effect of a larger assemblage, including the number of entries and diversity of functions. We argue that a focus on both measures is critical to understand the performance and potential transformation of street networks in a TOD.