Kampung is a historical form of vernacular urbanism in Indonesia with similar typologies occurring across Southeast Asia. As an urban form, it plays a crucial role in absorbing rural–urban migration symptomatic of not only postcolonial urbanisation in the Global South, but also precolonial and colonial trade networks. Kampung’s adaptability in accommodating diverse aspirations and cultural influences makes it no less cosmopolitan than the formally planned cities it was situated in. This paper examines kampung’s urbanism in contemporary Indonesia and theorises it as a form of subaltern cosmopolitanism. It reveals the interlaces of a localised regional practice of bottom-up urbanism with subnational and transnational professional design networks on the fringe of Indonesia’s most rapidly “worlding” urban centre outside Java: Makassar. It reveals how urbanity is produced through a coalescence of sub-national diversity, mobile intellectual actors, and transnational network of design activism that spans the developing urban region of the Global South.